Columbia Property Trust (CXP) 10-K 15 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Jan. 31, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	COLUMBIA PROPERTY TRUST, INC.
Entity Central Index Key	1,252,849
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		119,897,777
Entity Public Float			$ 2,286,239
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Real Estate Assets, at Cost:
Land	$ 825,208	$ 751,351
Buildings and improvements, less accumulated depreciation of $388,796 and $435,457, as of December 31, 2017 and 2016, respectively	2,063,419	2,121,150
Intangible lease assets, less accumulated amortization of $94,065 and $112,777, as of December 31, 2017 and 2016, respectively	199,260	193,311
Construction in progress	44,742	36,188
Real estate assets held for sale, less accumulated depreciation and amortization of $180,791 as of December 31, 2016	0	412,506
Total real estate assets	3,132,629	3,514,506
Investment in unconsolidated joint ventures	943,242	127,346
Cash and cash equivalents	9,567	216,085
Tenant receivables, net of allowance for doubtful accounts of $0 and $31 as of December 31, 2017 and 2016, respectively	2,128	7,163
Straight-line rent receivable	92,235	64,811
Prepaid expenses and other assets	27,683	24,275
Intangible lease origination costs, less accumulated amortization of $57,465 and $74,578, as of December 31, 2017 and 2016, respectively	42,959	54,279
Deferred lease costs, less accumulated amortization of $26,464 and $22,753, as of December 31, 2017 and 2016, respectively	141,096	125,799
Investment in development authority bonds	120,000	120,000
Other assets held for sale, less accumulated amortization of $34,152 as of December 31, 2016	0	45,529
Total assets	4,511,539	4,299,793
Liabilities:
Line of credit and notes payable, net of deferred financing costs of $2,991 and $3,136, as of December 31, 2017 and 2016, respectively	971,185	721,466
Bonds payable, net of discount of $1,484 and $1,664 and deferred financing costs of $4,760 and $5,364, as of December 31, 2017 and 2016, respectively	693,756	692,972
Accounts payable, accrued expenses, and accrued capital expenditures	125,002	131,028
Dividends payable	23,961	36,727
Deferred income	18,481	19,694
Intangible lease liabilities, less accumulated amortization of $19,660 and $44,564, as of December 31, 2017 and 2016, respectively	27,218	33,375
Obligations under capital leases	120,000	120,000
Liabilities held for sale, less accumulated amortization of $1,239 as of December 31, 2016	0	41,763
Total liabilities	1,979,603	1,797,025
Commitments and Contingencies (Note 7)
Equity:
Common stock, $0.01 par value, 225,000,000 shares authorized, 119,789,106 and 122,184,193 shares issued and outstanding as of December 31, 2017 and 2016, respectively	1,198	1,221
Additional paid-in capital	4,487,071	4,538,912
Cumulative distributions in excess of earnings	(1,957,236)	(2,036,482)
Accumulated other comprehensive income (loss)	903	(883)
Total equity	2,531,936	2,502,768
Total liabilities and equity	$ 4,511,539	$ 4,299,793

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Building and improvements, accumulated depreciation	$ 388,796	$ 435,457
Intangible lease assets, accumulated amortization	94,065	112,777
Real estate held-for-sale, accumulated amortization		180,791
Allowance for doubtful accounts	0	31
Intangible lease origination costs, accumulated amortization	57,465	74,578
Deferred lease costs, accumulated amortization	26,464	22,753
Other assets held for sale, accumulated amortization		34,152
Deferred financing costs	2,991	3,136
Bonds payable, discount	1,484	1,664
Intangible lease liabilities, accumulated amortization	$ 19,660	44,564
Liabilities held for sale, accumulated amortization		$ 1,239
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	225,000,000	225,000,000
Common stock, shares issued	119,789,106	122,184,193
Common stock, shares outstanding	119,789,106	122,184,193
Term Loans
Deferred financing costs	$ 2,991	$ 3,136
Bonds Payable
Deferred financing costs	$ 4,760	$ 5,364

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Rental income									$ 257,059	$ 366,186	$ 436,048
Tenant reimbursements									23,511	69,770	99,655
Hotel income									1,339	22,661	24,309
Asset and property management fee income									3,782	2,122	605
Other property income									3,309	12,804	5,448
Revenues	$ 71,625	$ 60,362	$ 74,857	$ 82,156	$ 105,768	$ 113,266	$ 127,930	$ 126,579	289,000	473,543	566,065
Expenses:
Property operating costs									87,805	154,968	188,078
Hotel operating costs									2,089	18,686	19,615
Asset and property management fee expenses									918	1,415	1,816
Depreciation									80,394	108,543	131,490
Amortization									32,403	56,775	87,128
General and administrative – corporate									34,966	33,876	29,683
General and administrative – unconsolidated joint ventures									1,454	0	0
Acquisition expenses									0	0	3,675
Costs and expenses									240,029	374,263	461,485
Real estate operating income (loss)									48,971	99,280	104,580
Other Income (Expense):
Interest expense									(60,516)	(67,609)	(85,296)
Interest and other income									9,529	7,288	7,254
Loss on interest rate swaps									0	0	(1,110)
Loss on the early extinguishment of debt		102,400							(325)	(18,997)	(3,149)
Nonoperating income (expense)									(51,312)	(79,318)	(82,301)
Income (loss) before income tax, unconsolidated joint ventures, and gains on sales of real estate assets									(2,341)	19,962	22,279
Income tax benefit (expense)									213	(445)	(378)
Income (loss) from unconsolidated joint ventures									2,651	(7,561)	(1,142)
Income before gains on sales of real estate assets									523	11,956	20,759
Gains on sales of real estate assets									175,518	72,325	23,860
Net income	$ (1,348)	$ 101,534	$ 1,133	$ 74,722	$ 27,400	$ 36,898	$ 13,286	$ 6,697	$ 176,041	$ 84,281	$ 44,619
Per-Share Information – Basic:
Net income (in dollars per share)	$ (0.01)	$ 0.84	$ 0.01	$ 0.61	$ 0.22	$ 0.30	$ 0.11	$ 0.05	$ 1.45	$ 0.68	$ 0.36
Weighted-average common shares outstanding – basic (in shares)									120,795	123,130	124,757
Per-Share Information – Diluted:
Net income (in dollars per share)	$ (0.01)	$ 0.84	$ 0.01	$ 0.61	$ 0.22	$ 0.30	$ 0.11	$ 0.05	$ 1.45	$ 0.68	$ 0.36
Weighted-average common shares – diluted (in shares)									121,159	123,228	124,847

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ (1,348)	$ 101,534	$ 1,133	$ 74,722	$ 27,400	$ 36,898	$ 13,286	$ 6,697	$ 176,041	$ 84,281	$ 44,619
Market value adjustment to interest rate swap									1,786	1,553	(1,570)
Settlement of interest rate swap									0	0	1,102
Comprehensive income									$ 177,827	$ 85,834	$ 44,151

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Cumulative Distributions in Excess of Earnings	Accumulated Other Comprehensive Income (Loss)
Balance, shares at beginning of period at Dec. 31, 2014		124,973,000
Balance, value at beginning of period at Dec. 31, 2014	$ 2,733,478	$ 1,249	$ 4,601,808	$ (1,867,611)	$ (1,968)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchases of common stock, shares		(721,000)
Repurchases of common stock	(16,335)	$ (7)	(16,328)
Common stock issued to employees and directors, and amortized (net of income tax witholdings), shares		111,000
Common stock issued to employees and directors, and amortized (net of income tax witholdings)	2,824	$ 1	2,823
Distributions to common stockholders	(149,924)			(149,924)
Net income	44,619			44,619
Market value adjustment to interest rate swap	(1,570)				(1,570)
Settlement of interest rate swap	1,102				1,102
Balance, shares at end of period at Dec. 31, 2015		124,363,000
Balance, value at end of period at Dec. 31, 2015	2,614,194	$ 1,243	4,588,303	(1,972,916)	(2,436)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchases of common stock, shares		(2,399,000)
Repurchases of common stock	(52,801)	$ (24)	(52,777)
Common stock issued to employees and directors, and amortized (net of income tax witholdings), shares		220,000
Common stock issued to employees and directors, and amortized (net of income tax witholdings)	3,388	$ 2	3,386
Distributions to common stockholders	(147,847)			(147,847)
Net income	84,281			84,281
Market value adjustment to interest rate swap	1,553				1,553
Settlement of interest rate swap	$ 0
Balance, shares at end of period at Dec. 31, 2016	122,184,193	122,184,000
Balance, value at end of period at Dec. 31, 2016	$ 2,502,768	$ 1,221	4,538,912	(2,036,482)	(883)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchases of common stock, shares		(2,682,000)
Repurchases of common stock	(57,628)	$ (26)	(57,602)
Common stock issued to employees and directors, and amortized (net of income tax witholdings), shares		287,000
Common stock issued to employees and directors, and amortized (net of income tax witholdings)	5,764	$ 3	5,761
Distributions to common stockholders	(96,795)			(96,795)
Net income	176,041			176,041
Market value adjustment to interest rate swap	1,786				1,786
Settlement of interest rate swap	$ 0
Balance, shares at end of period at Dec. 31, 2017	119,789,106	119,789,000
Balance, value at end of period at Dec. 31, 2017	$ 2,531,936	$ 1,198	$ 4,487,071	$ (1,957,236)	$ 903

Consolidated Statements of Equ7

Consolidated Statements of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common Stock
Distributions to common stockholders (in dollars per share)	$ 0.80	$ 1.20	$ 1.20

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows from Operating Activities:
Net income	$ 176,041	$ 84,281	$ 44,619
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Straight-line rental income	(32,737)	(21,875)	(16,632)
Depreciation	80,394	108,543	131,490
Amortization	31,907	52,530	78,000
Noncash interest expense	3,009	3,549	4,335
Loss on early extinguishment of debt	325	18,997	3,149
Gain on interest rate swaps	0	0	(1,532)
Gains on sales of real estate assets	(175,518)	(72,325)	(23,860)
Loss (income) from unconsolidated joint ventures	(2,651)	7,561	1,142
Distributions of earnings from unconsolidated joint ventures	3,681	0	0
Stock-based compensation expense	7,580	4,558	3,548
Changes in Assets and Liabilities, Net of Acquisitions and Dispositions:
Decrease (increase) in tenant receivables, net	4,222	4,251	(4,414)
Decrease (increase) in prepaid expenses and other assets	(1,754)	5,533	(2,155)
Increase (decrease) in accounts payable and accrued expenses	(28,133)	(1,607)	3,330
Increase (decrease) in deferred income	(4,442)	(905)	2,060
Net cash provided by operating activities	61,924	193,091	223,080
Cash Flows From Investing Activities:
Net proceeds from the sale of real estate	737,631	603,732	596,734
Real estate acquisitions	(604,769)	0	(1,062,031)
Deposits	0	10,000	0
Capital improvements and development costs	(86,805)	(39,521)	(83,371)
Deferred lease costs paid	(26,722)	(32,386)	(22,531)
Investments in unconsolidated joint ventures	(369,043)	(16,212)	(5,500)
Distributions in excess of earnings from unconsolidated joint ventures	1,985	0	0
Net cash provided by (used in) investing activities	(347,723)	525,613	(576,699)
Cash Flows From Financing Activities:
Financing costs paid	(1,269)	(3,114)	(9,729)
Prepayments to settle debt and interest rate swap	0	(17,921)	(3,165)
Proceeds from lines of credit and notes payable	783,000	435,000	1,884,000
Repayments of lines of credit and notes payable	(533,427)	(845,460)	(1,854,512)
Proceeds from issuance of bonds payable	0	348,691	349,507
Repayment of bonds payable	0	(250,000)	0
Distributions paid to stockholders	(109,561)	(148,474)	(112,570)
Redemptions of common stock	(59,462)	(53,986)	(17,057)
Net cash provided by (used in) financing activities	79,281	(535,264)	236,474
Net increase (decrease) in cash and cash equivalents	(206,518)	183,440	(117,145)
Cash and cash equivalents, beginning of period	216,085	32,645	149,790
Cash and cash equivalents, end of period	$ 9,567	$ 216,085	$ 32,645

Organization

Organization	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Columbia Property Trust, Inc. ("Columbia Property Trust") (NYSE: CXP) is a Maryland corporation that operates as a real estate investment trust ("REIT") for federal income tax purposes and owns and operates commercial real estate properties. Columbia Property Trust was incorporated in 2003, commenced operations in 2004, and conducts business primarily through Columbia Property Trust Operating Partnership, L.P. ("Columbia Property Trust OP"), a Delaware limited partnership. Columbia Property Trust is the general partner and sole owner of Columbia Property Trust OP and possesses full legal control and authority over its operations. Columbia Property Trust OP acquires, redevelops, owns, leases, and operates real properties directly, through wholly owned subsidiaries, or through unconsolidated joint ventures. Unless otherwise noted, references to Columbia Property Trust, "we," "us," or "our" herein shall include Columbia Property Trust and all subsidiaries of Columbia Property Trust, direct and indirect. Columbia Property Trust typically invests in high-quality, income-generating office properties. As of December 31, 2017 , Columbia Property Trust owned 19 operating properties, of which 14 were wholly owned and five were owned through unconsolidated joint ventures. These properties are located primarily in New York, San Francisco, Washington, D.C., and Atlanta, contain a total of 9.2 million rentable square feet, and were approximately 96.2% leased as of December 31, 2017 .

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The consolidated financial statements of Columbia Property Trust have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") and include the accounts of Columbia Property Trust, Columbia Property Trust OP, and any variable interest entity ("VIE") in which Columbia Property Trust or Columbia Property Trust OP was deemed the primary beneficiary. With respect to entities that are not VIEs, Columbia Property Trust's consolidated financial statements shall also include the accounts of any entity in which Columbia Property Trust, Columbia Property Trust OP, or its subsidiaries own a controlling financial interest and any limited partnership in which Columbia Property Trust, Columbia Property Trust OP, or its subsidiaries own a controlling general partnership interest. In determining whether Columbia Property Trust or Columbia Property Trust OP has a controlling interest, the following factors are considered, among other things: the ownership of voting interests, protective rights, and participatory rights of the investors. All intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying consolidated financial statements and the accompanying notes. Actual results could differ from those estimates. Fair Value Measurements Columbia Property Trust estimates the fair value of its assets and liabilities (where currently required under GAAP) consistent with the provisions of Accounting Standard Codification 820, Fair Value Measurements ("ASC 820"). Under this standard, fair value is defined as the price that would be received upon sale of an asset or paid upon transfer of a liability in an orderly transaction between market participants at the measurement date. While various techniques and assumptions can be used to estimate fair value depending on the nature of the asset or liability, the accounting standard for fair value measurements and disclosures provides the following fair value technique parameters and hierarchy, depending upon availability: Level 1 – Assets or liabilities for which the identical term is traded on an active exchange, such as publicly traded instruments or futures contracts. Level 2 – Assets and liabilities valued based on observable market data for similar instruments. Level 3 – Assets or liabilities for which significant valuation assumptions are not readily observable in the market. Such assets or liabilities are valued based on the best available data, some of which may be internally developed. Significant assumptions may include risk premiums that a market participant would consider. Real Estate Assets Real estate assets are stated at cost, less accumulated depreciation and amortization. Amounts capitalized to real estate assets consist of the cost of acquisition or construction, and any tenant improvements or major improvements and betterments that extend the useful life of the related asset. All repairs and maintenance are expensed as incurred. Additionally, Columbia Property Trust capitalizes interest while the development of a real estate asset is in progress. During the years ended December 31, 2017 and 2016 , $0.7 million and $0.3 million of interest was capitalized, respectively. Columbia Property Trust is required to make subjective assessments as to the useful lives of its depreciable assets. To determine the appropriate useful life of an asset, Columbia Property Trust considers the period of future benefit of the asset. These assessments have a direct impact on net income. The estimated useful lives of its assets by class are as follows: Buildings 40-45 years Building and site improvements 5-25 years Tenant improvements Shorter of economic life or lease term Intangible lease assets Lease term Evaluating the Recoverability of Real Estate Assets Columbia Property Trust continually monitors events and changes in circumstances that could indicate that the carrying amounts of its real estate and related intangible assets, of both operating properties and properties under construction, may not be recoverable. When indicators of potential impairment are present that suggest that the carrying amounts of real estate assets and related intangible assets (liabilities) may not be recoverable, Columbia Property Trust assesses the recoverability of these assets by determining whether the respective carrying values will be recovered through the estimated undiscounted future operating cash flows expected from the use of the assets and their eventual disposition. In the event that such expected undiscounted future cash flows do not exceed the carrying values, Columbia Property Trust adjusts the carrying value of the real estate assets and related intangible assets to the estimated fair values, pursuant to the property, plant, and equipment accounting standard for the impairment or disposal of long-lived assets, and recognizes an impairment loss. Estimated fair values are calculated based on the following hierarchy of information: (Level 1) recently quoted market prices, (Level 2) market prices for comparable properties, or (Level 3) the present value of future cash flows, including estimated residual value. Certain of Columbia Property Trust's assets may be carried at an amount that exceeds that which could be realized in a current disposition transaction. Columbia Property Trust has determined that the carrying values of its real estate assets and related intangible assets are recoverable as of December 31, 2017 . Projections of expected future operating cash flows require that Columbia Property Trust estimates future market rental income amounts subsequent to the expiration of current lease agreements, property operating expenses, the number of months it takes to re-lease the property, and the number of years the property is held for investment, among other factors. Due to the inherent subjectivity of the assumptions used to project future cash flows, estimated fair values may differ from the values that would be realized in market transactions. Assets Held for Sale Columbia Property Trust classifies properties as held for sale according to Accounting Standard Codification 360, Accounting for the Impairment or Disposal of Long-Lived Assets ("ASC 360"). According to ASC 360, properties, having separately identifiable operations and cash flows, are considered held for sale when the following criteria are met: • Management, having the authority to approve the action, commits to a plan to sell the property. • The property is available for immediate sale in its present condition subject only to terms that are usual and customary for sales of such property. • An active program to locate a buyer and other actions required to complete the plan to sell the property have been initiated. • The property is being actively marketed for sale at a price that is reasonable in relation to its current fair value. • Actions required to complete the plan indicate that it is unlikely that significant changes to the plan will be made or that the plan will be withdrawn. • The sale of the property is probable (i.e. typically subject to a binding sale contract with a non-refundable deposit), and transfer of the property is expected to qualify for recognition as a completed sale, within one year. At such time that a property is determined to be held for sale, its carrying amount is adjusted to the lower of its depreciated book value or its estimated fair value, less costs to sell, and depreciation is no longer recognized; and assets and liabilities are required to be classified as held for sale on the accompanying consolidated balance sheet. As of December 31, 2017 , none of Columbia Property Trust's properties met the criteria to be classified as held for sale in the accompanying consolidated balance sheet. As of December 31, 2016, Key Center Tower, Key Center Marriott, 5 Houston Center, Energy Center I, and 515 Post Oak were subject to binding sale contracts and met the other aforementioned criteria; thus, these properties are classified as held for sale in the accompanying consolidated balance sheet as of that date. The sale of 5 Houston Center, Energy Center I, and 515 Post Oak closed on January 6, 2017, and the sale of Key Center Tower and Key Center Marriott closed on January 31, 2017 (see Note 3, Real Estate Transactions ). The major classes of assets and liabilities classified as held for sale as of December 31, 2016 , are provided below (in thousands): December 31, 2016 Real Estate Assets Held for Sale: Real Estate Assets, at Cost: Land $ 30,243 Buildings and improvements, less accumulated depreciation of $152,246 366,126 Intangible lease assets, less accumulated amortization of $28,545 13,365 Construction in progress 2,772 Total real estate assets held for sale, net $ 412,506 Other Assets Held for Sale: Tenant receivables, net of allowance for doubtful accounts $ 1,722 Straight-line rent receivable 20,221 Prepaid expenses and other assets 3,184 Intangible lease origination costs, less accumulated amortization of $22,949 1,815 Deferred lease costs, less accumulated amortization of $11,203 18,587 Total other assets held for sale, net $ 45,529 Liabilities Held for Sale: Accounts payable, accrued expenses, and accrued capital expenditures $ 34,812 Deferred income 4,214 Intangible lease liabilities, less accumulated amortization of $1,239 2,737 Total liabilities held for sale, net $ 41,763 Allocation of Purchase Price of Acquired Assets Upon the acquisition of real properties, Columbia Property Trust allocates the purchase price of properties to tangible assets, consisting of land, building, site improvements, and identified intangible assets and liabilities, including the value of in-place leases, based in each case on Columbia Property Trust's estimate of their fair values in accordance with ASC 820 (see Fair Value Measurements section above for additional details). Columbia Property Trust adopted ASU 2017-01, as described in the Recent Accounting Pronouncements section below, effective October 1, 2017. As a result, transaction costs for properties acquired in the fourth quarter have been capitalized and included in the purchase price allocated for properties acquired in the period. Prior to October 1, 2017, transaction costs were expensed and included in acquisition expense on the accompanying statements of operations. The fair values of the tangible assets of an acquired property (which includes land, building, and site improvements) are determined by valuing the property as if it were vacant, and the "as-if-vacant" value is then allocated to land, building, and site improvements based on management's determination of the relative fair value of these assets. Management determines the as-if-vacant fair value of a property using methods similar to those used by independent appraisers. Factors considered by management in performing these analyses include an estimate of carrying costs during the expected lease-up periods considering current market conditions and costs to execute similar leases, including leasing commissions and other related costs. In estimating carrying costs, management includes real estate taxes, insurance, and other operating expenses during the expected lease-up periods based on current market demand. Intangible Assets and Liabilities Arising From In-Place Leases Where Columbia Property Trust Is the Lessor As further described below, in-place leases with Columbia Property Trust as the lessor may have values related to: direct costs associated with obtaining a new tenant, opportunity costs associated with lost rentals that are avoided by acquiring an in-place lease, tenant relationships, and effective contractual rental rates that are above or below market rates: • Direct costs associated with obtaining a new tenant, including commissions, tenant improvements, and other direct costs, are estimated based on management's consideration of current market costs to execute a similar lease. Such direct costs are included in intangible lease origination costs in the accompanying consolidated balance sheets and are amortized to expense over the remaining terms of the respective leases. • The value of opportunity costs associated with lost rentals avoided by acquiring an in-place lease is calculated based on contractual amounts to be paid pursuant to the in-place leases over a market absorption period for a similar lease. Such opportunity costs ("Absorption Period Costs") are included in intangible lease assets in the accompanying consolidated balance sheets and are amortized to expense over the remaining terms of the respective leases. • The value of effective rental rates of in-place leases that are above or below the market rates of comparable leases is calculated based on the present value (using a discount rate that reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be received pursuant to the in-place leases and (ii) management's estimate of fair market lease rates for the corresponding in-place leases. This calculation includes significantly below- market renewal options for which exercise of the renewal option appears to be reasonably assured. These intangible assets or liabilities are measured over the actual or assumed (in the case of renewal options) remaining lease terms. The capitalized above-market and below-market lease values are recorded as intangible lease assets or liabilities and amortized as an adjustment to rental income over the remaining terms of the respective leases. As of December 31, 2017 and 2016 , Columbia Property Trust had the following gross intangible in-place lease assets and liabilities, excluding amounts held for sale (in thousands): Intangible Lease Assets Intangible Lease Origination Costs Intangible Below-Market In-Place Lease Liabilities Above-Market In-Place Lease Assets Absorption Period Costs December 31, 2017 Gross $ 2,481 $ 149,927 $ 100,424 $ 46,878 Accumulated Amortization (833 ) (70,465 ) (57,465 ) (19,660 ) Net $ 1,648 $ 79,462 $ 42,959 $ 27,218 December 31, 2016 Gross $ 10,589 $ 154,582 $ 128,857 $ 77,939 Accumulated Amortization (9,305 ) (83,254 ) (74,578 ) (44,564 ) Net $ 1,284 $ 71,328 $ 54,279 $ 33,375 During 2017 , 2016 , and 2015 , Columbia Property Trust recognized the following amortization of intangible lease assets and liabilities (in thousands): Intangible Lease Assets Intangible Lease Origination Costs Intangible Below-Market In-Place Lease Liabilities Above-Market In-Place Lease Assets Absorption Period Costs For the Years Ended December 31, 2017 $ 519 $ 16,807 $ 10,124 $ 6,883 2016 $ 2,513 $ 28,718 $ 17,501 $ 12,996 2015 $ 4,412 $ 45,972 $ 28,530 $ 19,345 The remaining net intangible assets and liabilities as of December 31, 2017 , excluding amounts held for sale, will be amortized as follows (in thousands): Intangible Lease Assets Intangible Lease Origination Costs Intangible Below-Market In-Place Lease Liabilities Above-Market In-Place Lease Assets Absorption Period Costs For the Years Ending December 31, 2018 $ 203 $ 16,898 $ 9,566 $ 6,325 2019 203 14,665 8,651 5,968 2020 203 12,800 7,770 4,535 2021 203 8,112 3,727 1,591 2022 203 6,585 2,708 1,287 Thereafter 633 20,402 10,537 7,512 $ 1,648 $ 79,462 $ 42,959 $ 27,218 Weighted-average amortization period 8 years 5 years 5 years 6 years Intangible Assets and Liabilities Arising From In-Place Leases Where Columbia Property Trust Is the Lessee In-place ground leases where Columbia Property Trust is the lessee may have positive or negative value associated with effective contractual rental rates that are above or below market rates at the time of execution or assumption. Such values are calculated based on the present value (using a discount rate that reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to the in-place lease and (ii) management's estimate of fair market lease rates for the corresponding in-place lease at the time of execution or assumption. This calculation includes significantly below-market renewal options for which exercise of the renewal option appears to be reasonably assured. These intangible assets and liabilities are measured over the actual or assumed (in the case of renewal options) remaining lease terms. The capitalized above-market and below-market in-place lease values are recorded as intangible lease liabilities and assets, respectively, and are amortized as an adjustment to property operating cost over the remaining term of the respective leases. Columbia Property Trust had gross below-market lease assets of approximately $140.9 million as of December 31, 2017 and 2016 , net of accumulated amortization of $22.8 million and $20.2 million as of December 31, 2017 and 2016 , respectively. Columbia Property Trust recognized amortization expense related to these assets of approximately $2.5 million for 2017 , 2016 , and 2015 . As of December 31, 2017 , the remaining net below-market lease asset will be amortized as follows (in thousands): For the Years Ending December 31: 2018 $ 2,549 2019 2,549 2020 2,549 2021 2,549 2022 2,549 Thereafter 105,405 $ 118,150 Weighted-average amortization period 47 years Cash and Cash Equivalents Columbia Property Trust considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. Cash equivalents may include cash and short-term investments. Short-term investments are stated at cost, which approximates fair value as of December 31, 2017 and 2016 . Tenant Receivables, Net Tenant receivables consist of rental and reimbursement billings due from tenants. Tenant receivables are recorded at the original amount earned, less an allowance for any doubtful accounts, which approximates fair value. Management assesses the realizability of tenant receivables on an ongoing basis and provides for allowances as such balances, or portions thereof, become uncollectible. Columbia Property Trust adjusted the allowance for doubtful accounts by recording a provision for doubtful accounts, net of recoveries, in general and administrative expenses in the accompanying consolidated statements of operations of approximately $26,000 and $289,000 for 2017 and 2016 , respectively. Straight Line Rent Receivable Straight line rent receivable reflects the amount of cumulative adjustments necessary to present rental income on a straight-line basis. Columbia Property Trust recognizes revenues on a straight-line basis, ratably over the term of each lease; however, leases often provide for payment terms that differ from the revenue recognized. When the amount of cash received is less than the amount of revenue recognized, typically early in the lease, straight line rent receivable is recorded for the difference. The receivable is depleted during periods later in the lease when the amount of cash paid by the tenant is greater than the amount of revenue recognized. Prepaid Expenses and Other Assets Prepaid expenses and other assets primarily include earnest money deposits, escrow accounts held by lenders to pay future real estate taxes, insurance and tenant improvements, notes receivable, nontenant receivables, prepaid taxes, insurance and operating costs, unamortized deferred financing costs related to the line of credit (the "Revolving Credit Facility"), interest rate swaps (when in an asset position), certain corporate assets, hotel inventory, and deferred tax assets. Prepaid expenses are recognized over the period to which the good or service relates. Other assets are written off when the asset no longer has future value, or when the company is no longer obligated for the corresponding liability. Deferred Financing Costs Deferred financing costs include costs incurred to secure debt from third-party lenders. Deferred financing costs, except for costs related to the Revolving Credit Facility, are presented as a direct reduction to the carrying amount of the related debt for all periods presented. Deferred financing costs related to the Revolving Credit Facility are included in prepaid expenses and other assets. Columbia Property Trust recognized amortization of deferred financing costs for the years ended December 31, 2017 , 2016 , and 2015 of approximately $2.8 million , $3.3 million , and $4.4 million , respectively, which is included in interest expense in the accompanying consolidated statements of operations. Deferred Lease Costs Deferred lease costs include costs incurred to procure leases that are paid to third parties or tenants, and incentives that are provided to tenants under the terms of their leases. These costs are capitalized and amortized on a straight-line basis over the terms of the lease. Amortization of third-party leasing costs is reflected as amortization expense, and amortization of lease incentives is reflected as an adjustment to rental income. During 2017 , 2016 , and 2015 , Columbia Property Trust recognized amortization expense for deferred lease costs of $5.2 million , $9.3 million , and $8.9 million , respectively. During 2017 , 2016 , and 2015 , Columbia Property Trust recognized adjustments to rental income for amortization of deferred lease costs of $3.3 million , $3.9 million , and $3.7 million , respectively. Upon receiving notification of a tenant's intention to terminate a lease, unamortized deferred lease costs are amortized over the shortened lease period. As of December 31, 2017 and 2016 , deferred lease costs includes $68.4 million and $69.0 million , respectively, in unamortized lease incentives for a lease at the 222 East 41st Street Property, which will continue to be amortized to rental income over the approximately 30 -year remaining lease term. Investments in Development Authority Bonds and Obligations Under Capital Leases In connection with the acquisition of certain real estate assets, Columbia Property Trust has assumed investments in development authority bonds and corresponding obligations under capital leases of land or buildings. The county development authority issued bonds to developers to finance the initial development of these projects, a portion of which was then leased back to the developer under a capital lease. This structure enabled the developer to receive property tax abatements over the concurrent terms of the development authority bonds and capital leases. The remaining property tax abatement benefits transferred to Columbia Property Trust upon assumption of the bonds and corresponding capital leases at acquisition. The development authority bonds and the obligations under the capital leases are both recorded at their net present values, which Columbia Property Trust believes approximates fair value. The related amounts of interest income and expense are recognized as earned in equal amounts and, accordingly, do not impact net income. Accounts Payable, Accrued Expenses, and Accrued Capital Expenditures Accounts payable, accrued expenses, and accrued capital expenditures primarily include payables related to property operations, capital projects, and interest rate swaps (when in a liability position). As of December 31, 2017 and 2016 , a ccounts payable, accrued expenses, and accrued capital expenditures includes approximately $54.7 million and $69.0 million in lease incentives related to a lease at the 222 East 41st Street Property . Line of Credit and Notes Payable Certain mortgage notes included in line of credit and notes payable in the accompanying consolidated balance sheets were assumed upon the acquisition of real properties. When debt is assumed, Columbia Property Trust records the loan at fair value. The fair value adjustment is amortized to interest expense over the term of the loan using the effective interest method. As described in the Deferred Financing Costs section above, line of credit and notes payable is presented on the accompanying consolidated balance sheet net of deferred financing costs related to term loans and notes payable of $3.0 million and $3.1 million as of December 31, 2017 and December 31, 2016 , respectively. Bonds Payable In August 2016, Columbia Property Trust issued $350 million of its 10 -year unsecured 3.650% senior notes at 99.626% of their face value (the "2026 Bonds Payable"). In March 2015, Columbia Property Trust issued $350.0 million of its 10 -year unsecured 4.150% senior notes at 99.859% of their face value (the "2025 Bonds Payable"). The discount on the 2026 Bonds Payable and the 2025 Bonds Payable is amortized to interest expense over the term of the bonds using the effective-interest method. As described in the Deferred Financing Costs section above, bonds payable are presented on the accompanying consolidated balance sheet net of deferred financing costs related to bonds payable of $4.8 million and $5.4 million as of December 31, 2017 and December 31, 2016 , respectively. Common Stock Repurchase Program Columbia Property Trust's board of directors has authorized the repurchases of its common stock, par value $0.01 per share, subject to certain limitations, as described in Note 8, Equity . Columbia Property Trust expects to acquire shares primarily through open market transactions, subject to market conditions and other factors. As of December 31, 2017 , $194.8 million remains available for repurchases under the current stock repurchase program. Common stock repurchases are charged against equity as incurred, and the repurchased shares are retired. See Note 8, Equity , for additional details. Preferred Stock Columbia Property Trust is authorized to issue up to 100.0 million shares of one or more classes or series of preferred stock with a par value of $0.01 per share. Columbia Property Trust's board of directors may determine the relative rights, preferences, and privileges of each class or series of preferred stock issued, which may be more beneficial than the rights, preferences, and privileges attributable to Columbia Property Trust's common stock. To date, Columbia Property Trust has not issued any shares of preferred stock. Common Stock The par value of Columbia Property Trust's issued and outstanding shares of common stock is classified as common stock, with the remainder allocated to additional paid-in capital. Distributions To maintain its status as a REIT, Columbia Property Trust is required by the Internal Revenue Code of 1986, as amended (the "Code"), to make distributions to stockholders each taxable year equal to at least 90% of its REIT taxable income, computed without regard to the dividends-paid deduction and by excluding net capital gains attributable to stockholders ("REIT taxable income"). Distributions to the stockholders are determined by the board of directors of Columbia Property Trust and are dependent upon a number of factors relating to Columbia Property Trust, including funds available for payment of distributions, financial condition, the timing of property acquisitions, capital expenditure requirements, and annual distribution requirements in order to maintain Columbia Property Trust's status as a REIT under the Code. Interest Rate Swap Agreements Columbia Property Trust enters into interest rate swap contracts to mitigate its interest rate risk on the related financial instruments. Columbia Property Trust does not enter into derivative or interest rate transactions for speculative purposes; however, certain of its derivatives may not qualify for hedge accounting treatment. Columbia Property Trust records the fair value of its interest rate swaps on its consolidated balance sheet either as prepaid expenses and other assets or as accounts payable, accrued expenses, and accrued capital expenditures. Changes in the fair value of the effective portion of interest rate swaps that are designated as cash flow hedges are recorded as other comprehensive income, while changes in the fair value of the ineffective portion of a hedge, if any, is recognized currently in earnings. Changes in the fair value of interest rate swaps that do not qualify for hedge accounting treatment are recorded as gain or loss on interest rate swaps. Amounts received or paid under interest rate swap agreements are recorded as interest expense for contracts that qualify for hedge accounting treatment and as loss on interest rate swaps for contracts that do not qualify for hedge accounting treatment. The following tables provide additional information related to Columbia Property Trust's interest rate swaps as of December 31, 2017 and 2016 (in thousands): Estimated Fair Value as of December 31, Instrument Type Balance Sheet Classification 2017 2016 Derivatives Designated as Hedging Instruments: Interest rate contracts Prepaid expenses and other assets $ 903 $ — Interest rate contracts Accounts payable $ — $ (882 ) Columbia Property Trust applied the provisions of ASC 820 in recording its interest rate swaps at fair value. The fair values of the interest rate swaps, classified under Level 2, were determined using a third-party proprietary model that is based on prevailing market data for contracts with matching durations, current and anticipated London Interbank Offered Rate ("LIBOR") information, and reasonable estimates about relevant future market conditions. Columbia Property Trust has determined that the fair value, as determined by the third party, is reasonable. Years Ended December 31, 2017 2016 2015 Market value adjustment to interest rate swaps designated as hedging instruments and included in other comprehensive income $ 1,786 $ 1,553 $ (1,570 ) Loss on interest rate swap recognized through earnings $ — $ — $ (1,110 ) In July 2015, Columbia Property Trust paid $1.1 million to settle the interest rate swap on a $450 million term loan, which is reflected in earnings. During the periods presented, there was no other hedge ineffectiveness required to be recognized into earnings on the interest rate swaps that qualified for hedge accounting treatment. Revenue Recognition All leases on real estate assets held by Columbia Property Trust are classified as operating leases, and the related base rental income is generally recognized on a straight-line basis over the terms of the respective leases. Tenant reimbursements are recognized as revenue in the period that the related operating cost is incurred and are billed to tenants pursuant to the terms of the underlying leases. Rental income and tenant reimbursements collected in advance are recorded as deferred income in the accompanying consolidated balance sheets. Management fees earned by Columbia Property Trust for services provided to certain of its unconsolidated joint ventures are recorded as asset and property management fee income during the period in which such services are provided. Lease termination fees are recorded as other property income and recognized on a straight-line basis from when Columbia Property Trust receives notification of termination through the date the tenant has lost the right to lease the space and Columbia Property Trust has satisfied all obligations under the related lease or lease termination agreement. In conjunction with certain acquisitions, Columbia Property Trust has entered into master lease agreements with various sellers, whereby the sellers are obligated to pay rent pertaining to certain nonrevenue-producing spaces either at the time of, or subsequent to, the property acquisition. These master leases were established at the time of acquisition to mitigate the potential negative effects of lost rental revenues and expense reimbursement income. Columbia Property Trust records payments received under master lease agreements as a reduction of the basis of the underlying property rather than rental income. There were no proceeds received from master leases during 2017 , 2016 , or 2015 . Prior to disposition on January 31, 2017, Columbia Property Trust owned the Key Center Marriott, a full-service hotel, through a taxable REIT subsidiary. Revenues derived from the operations of the hotel include, but are not limited to, revenues from rental of rooms, food and beverage sales, telephone usage, and other service revenues. Revenue was recognized when rooms were occupied, when services performed, and when products were delivered. Income Taxes Columbia Property Trust has elected to be taxed as a REIT under the Code, and has operated as such beginning with its taxable year ended December 31, 2003. To

Real Estate Transactions

Real Estate Transactions	12 Months Ended
	Dec. 31, 2017
Business Acquisitions and Dispositions [Abstract]
Real Estate Transactions	Real Estate Transactions Acquisitions During 2017, 2016, and 2015, Columbia Property Trust acquired the following properties and partial interests in properties: Property Location Date Percent Acquired Purchase Price (1) 2017 149 Madison Avenue New York, NY November 28, 2017 100.0 % $ 87,700 1800 M Street Washington, D.C. October 11, 2017 55.0 % $ 231,550 (2) 245-249 West 17th Street & 218 West 18th Street New York, NY October 11, 2017 100.0 % $ 514,100 114 Fifth Avenue New York, NY July 6, 2017 49.5 % $ 108,900 (2) 2015 229 West 43rd Street New York NY August 4, 2015 100.0 % $ 516,000 116 Huntington Avenue Boston, MA January 8, 2015 100.0 % $ 152,000 315 Park Avenue South & 1881 Campus Commons New York, NY & Reston, VA January 7, 2015 100.0 % $ 436,000 (1) Exclusive of transaction costs and price adjustments. See purchase price allocation table below for a breakout of the net purchase price for wholly-owned properties. (2) Purchase price is for our partial interests in the properties. These properties are owned through unconsolidated joint ventures. 149 Madison Avenue 149 Madison Avenue is a 12-story, 127,000 -square-foot office building, which was vacant at the time of acquisition. Columbia Property Trust acquired 149 Madison Avenue subject to a ground lease which expired in January 2018. Columbia Property Trust plans to redevelop this property. For the period from November 28, 2017 to December 31, 2017, Columbia Property Trust recognized $10,300 of revenues and net income of $9,200 from 149 Madison Avenue. 1800 M Street Joint Venture Columbia Property Trust entered a new joint venture partnership with Allianz Real Estate of America LLC ("Allianz"), which simultaneously acquired 1800 M Street, a 10 -story, 581,000 -square-foot office building in Washington, D.C., that is 94% leased, for a total of $421.0 million (the "1800 M Street Joint Venture"). Columbia Property Trust owns a 55% interest in the 1800 M Street Joint Venture, and Allianz owns the remaining 45% . 245-249 West 17th Street & 218 West 18th Street 245-249 West 17th Street is made up of two interconnected 12- and six-story towers, totaling 281,000 square feet of office and retail space and 218 West 18th Street is a 12-story, 166,000 -square-foot office building. As of the acquisition date, 245-249 West 17th Street was 100% leased to four tenants, including Twitter, Inc. ( 76% ) and Room & Board, Inc. ( 21% ); and, as of the acquisition date, 218 West 18th Street was 100% leased to seven tenants, including Red Bull North America, Inc. ( 25% ), Company 3 ( 18% ), SY Partners ( 16% ), and SAE ( 16% ). For the period from October 11, 2017 to December 31, 2017, Columbia Property Trust recognized revenues of $5.9 million and a net income of $1.8 million from 245-249 West 17th Street, and revenues of $3.0 million and net income of $0.8 million from 218 West 18th Street. 114 Fifth Avenue Joint Venture Columbia Property Trust acquired a 49.5% equity interest in a joint venture that owns the 114 Fifth Avenue property from Allianz (the "114 Fifth Avenue Joint Venture"). 114 Fifth Avenue is a 19 -story, 352,000 -square-foot building located in Manhattan’s Flatiron District that is 100% leased, and is unencumbered by debt. The 114 Fifth Avenue Joint Venture is owned by Columbia Property Trust ( 49.5% ), Allianz ( 49.5% ), and L&L Holding Company ( 1.0% ). L&L Holding Company is the general partner and will continue to perform asset and property management services for the property. 229 West 43rd Street On August 4, 2015, Columbia Property Trust acquired the 481,000 -square-foot office portion of the 229 West 43rd Street, a 16 -story, 732,000 -square-foot building located in the Times Square sub-market of Manhattan in New York, New York, for $516.0 million , exclusive of transaction costs and purchase price adjustments. As of the acquisition date, the 229 West 43rd Street Building was 98.0% leased to nine tenants, including Yahoo! ( 40% ), Snapchat ( 13% ), Collective, Inc. ( 12% ), and MongoDB ( 10% ). For the period from August 4, 2015 to December 31, 2015, Columbia Property Trust recognized revenues of $15.3 million and net income of $2.2 million from the 229 West 43rd Street. The net income includes acquisition expenses of $1.7 million . 116 Huntington Avenue On January 8, 2015, Columbia Property Trust acquired 116 Huntington Avenue, a 271,000 -square-foot office building in Boston, Massachusetts, for $152.0 million , inclusive of capital credits. As of the acquisition date, the 116 Huntington Avenue Building was 78.0% leased to 17 tenants, including American Tower ( 21% ), GE Healthcare ( 13% ), and Brigham and Women's ( 12% ). For the period from January 8, 2015 to December 31, 2015, Columbia Property Trust recognized revenues of $11.3 million and a net loss of $0.7 million from the 116 Huntington Avenue. The net loss includes acquisition expenses of $0.3 million . 315 Park Avenue South Building & 1881 Campus Commons Building On January 7, 2015, Columbia Property Trust acquired a portfolio of two assets, which included 315 Park Avenue South, a 327,000 -square-foot office building in New York, New York, and 1881 Campus Commons, a 244,000 -square-foot office building in Reston, Virginia. This portfolio was acquired for $436.0 million , exclusive of transaction costs and purchase price adjustments. As of the acquisition date, the 315 Park Avenue South was 94.9% leased to nine tenants, including Credit Suisse ( 74% ). For the period from January 7, 2015 to December 31, 2015, Columbia Property Trust recognized revenues of $25.1 million and a net loss of $6.6 million from the 315 Park Avenue South. The net loss includes acquisition expenses of $1.2 million . As of the acquisition date, the 1881 Campus Commons was 78.0% leased to 15 tenants, including SOS International ( 15% ) and Siemens ( 12% ). For the period from January 7, 2015 to December 31, 2015, Columbia Property Trust recognized revenues of $5.8 million and a net loss of $1.3 million from the 1881 Campus Commons. The net loss includes acquisition expenses of $0.5 million . Columbia Property Trust sold 1881 Campus Commons on December 10, 2015, as described in the Dispositions section below. Purchase Price Allocations for Consolidated Property Acquisitions: 149 Madison Avenue 245-249 West 17th Street 218 West 18th Street 229 West 43rd Street 116 Huntington 315 Park Avenue 1881 Campus Commons Location New York, NY New York, NY New York, NY New York, NY Boston, MA New York, NY Reston, VA Date Acquired November 28, 2017 October 11, 2017 October 11, 2017 August 4, 2015 January 8, 2015 January 7, 2015 January 7, 2015 Purchase Price: Land $ 59,112 $ 113,149 $ 43,836 $ 207,233 — $ 119,633 $ 7,179 Building and improve-ments 28,989 194,109 126,957 265,952 108,383 232,598 49,273 Intangible lease assets — 27,408 12,120 27,039 7,907 16,912 4,643 Intangible below market ground lease assets — — — — 30,244 — — Intangible lease origin- ation costs — 13,062 4,168 10,059 2,669 4,148 1,603 Intangible below market lease liability — (7,131 ) (11,757 ) — (1,878 ) (7,487 ) (97 ) Total purchase price $ 88,101 $ 340,597 $ 175,324 $ 510,283 147,325 $ 365,804 $ 62,601 Note 2, Summary of Significant Accounting Policies , provides a discussion of the estimated useful life for each asset class. Pro Forma Financial Information: The following unaudited pro forma statements of operations presented for 2017 , 2016 , and 2015 , have been prepared for Columbia Property Trust to give effect to the acquisitions of 245-249 West 17th Street, 218 West 18th Street, and 149 Madison Avenue as if the acquisitions had occurred on January 1, 2016; and 315 Park Avenue South, 1881 Campus Commons, 116 Huntington Avenue, and 229 West 43rd Street as if the acquisitions had occurred on January 1, 2014. The following unaudited pro forma financial results for Columbia Property Trust have been prepared for informational purposes only and are not necessarily indicative of future results or of actual results that would have been achieved had these acquisitions been consummated as of January 1, 2016 and January 1, 2014 (in thousands): 2017 2016 2015 Revenues $ 319,064 $ 511,306 $ 582,699 Net income $ 183,318 $ 93,537 $ 46,363 Net income per share – basic $ 1.51 $ 0.76 $ 0.37 Net income per share – diluted $ 1.51 $ 0.76 $ 0.37 Dispositions During 2017 , 2016 , and 2015 , Columbia Property Trust sold the following properties and partial interest in properties: Property Location Date % Sold Sales Price (1) (in thousands) Gain (Loss) on Sale (rounded, in thousands) 2017 University Circle & 333 Market Street (2) San Francisco, CA July 6, 2017 22.5 % (3) $ 234,000 (2)(3) $ 102,400 Key Center Tower & Marriott (4) Cleveland, OH January 31, 2017 100.0 % $ 267,500 $ 9,500 Houston Properties (5) Houston, TX January 6, 2017 100.0 % $ 272,000 $ 63,700 2016 SanTan Corporate Center Phoenix, AZ December 15, 2016 100.0 % $ 58,500 $ 9,800 Sterling Commerce Dallas, TX November 30, 2016 100.0 % $ 51,000 $ 12,500 9127 South Jamaica Street Denver, CO October 12, 2016 100.0 % $ 19,500 $ — (6) 80 Park Plaza Newark, NJ September 30, 2016 100.0 % $ 174,500 $ 21,600 9189, 9191 & 9193 South Jamaica Street Denver, CO September 22, 2016 100.0 % $ 122,000 $ 27,200 800 North Frederick Suburban, MD July 8, 2016 100.0 % $ 48,000 $ 2,100 100 East Pratt (7) Baltimore, MD March 31, 2016 100.0 % $ 187,000 $ (300 ) 2015 1881 Campus Commons (8) Reston, VA December 10, 2015 100.0 % $ 65,000 $ 500 Market Square (9) Washington, D.C. October 28, 2015 49.0 % $ 291,600 (9) $ 3,100 11 Property Sale (10) Various (10) July 1, 2015 100.0 % $ 433,300 $ 20,200 (1) Exclusive of transaction costs and price adjustments. (2) Sales price is for the partial interests in the properties that were sold. Columbia Property Trust contributed the 333 Market Street building and the University Circle property to joint ventures, and simultaneously sold a 22.5% interest in those joint ventures for $234.0 million to Allianz, an unrelated third party (collectively, the "San Francisco Joint Ventures"). (3) On February 1, 2018, Allianz acquired another 22.5% interest in each of the San Francisco Joint Ventures at an aggregate price of $235.3 million , thereby reducing Columbia Property Trust's equity interest in each joint venture to 55.0% . These proceeds were used to reduce the balance on the $300 Million Bridge Loan and the Revolving Credit Facility, as described in Note 5, Line of Credit and Notes Payable . (4) Key Center Tower & Marriott were sold in one transaction for $254.5 million of gross proceeds and a $13.0 million , 10 -year accruing note receivable from the principal of the buyer. As a result, Columbia Property Trust has applied the installment method to account for this transaction, and deferred $13.0 million of the total $22.5 million gain on sale. The Key Center Tower and Key Center Marriott generated net income of $14.5 million and $12.1 million for the years ended December 31, 2016 and 2015, respectively; and a net loss of $1.9 million for the first 31 days of 2017, excluding the gain on sale. (5) 5 Houston Center, Energy Center I, and 515 Post Oak were sold in one transaction. These properties generated net income of $11.1 million and $12.9 million for the years ended December 31, 2016 and 2015, respectively; and a net loss of $14.9 thousand for the first six days of 2017, excluding the gain on sale. (6) Columbia Property Trust recorded a de minimus loss on the sale of 9127 South Jamaica Street. (7) The net sale proceeds of $159.4 million from 100 East Pratt were used to repay the $119.0 million remaining on the 2015 Bridge Loan on April 1, 2016. (8) The net proceeds from the sale of 1881 Campus Commons were used to reduce the outstanding balance of the 2015 Bridge Loan. (9) Sale price is for our partial interest in the property. On October 28, 2015, Columbia Property Trust transferred the Market Square properties, valued at $595.0 million and subject to a $325.0 million mortgage note, to a joint venture and sold a 49% interest in that joint venture to Blackstone Property Partners for net proceeds of approximately $120.0 million . Columbia Property Trust retains a 51% interest in the Market Square Joint Venture. See Note 4, Unconsolidated Joint Ventures , for additional information. (10) Columbia Property Trust closed on the sale of 11 properties on July 1, 2015 (the "11 Property Sale"). The 11 Property Sale included 170 and 180 Park Avenue in Northern New Jersey; 1580 West Nursery Road in Baltimore; Acxiom, Highland Landmark III, The Corridors III, 215 Diehl Road, 544 Lakeview, and Bannockburn Lake III in Chicago; and Robbins Road and 550 King Street in Boston. The proceeds for 10 of the properties were available on July 1, 2015, and the remaining proceeds were available on August 3, 2015. For the period from January 1, 2015 through July 1, 2015, the aggregate net income, excluding the gain on sale, for the properties included in the 11 Property Sale was $6.5 million ; and for the year ended December 31, 2015 , the net income for the properties included in the 11 Property Sale was $3.0 million , excluding the gain on sale.

Unconsolidated Joint Ventures

Unconsolidated Joint Ventures	12 Months Ended
	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Unconsolidated Joint Ventures	Unconsolidated Joint Ventures As of December 31, 2017 and December 31, 2016 , Columbia Property Trust owns interests in the following properties through joint ventures, which are accounted for using the equity method of accounting: Carrying Value of Investment Joint Venture (1) Property Name Geographic Market Ownership Interest December 31, 2017 December 31, 2016 Market Square Joint Venture Market Square Washington, D.C. 51.0 % $ 128,411 $ 127,346 University Circle Joint Venture University Circle San Francisco 77.5 % (2) 173,798 — 333 Market Street Joint Venture 333 Market Street San Francisco 77.5 % (2) 288,236 — 114 Fifth Avenue Joint Venture 114 Fifth Avenue New York 49.5 % 110,311 — 1800 M Street Joint Venture 1800 M Street Washington, D.C. 55.0 % 242,486 — $ 943,242 $ 127,346 (1) See Note 3, Real Estate Transactions, for a description of the formation of these joint ventures. (2) On February 1, 2018, Allianz acquired from Columbia Property Trust an additional 22.5% interest in each of the University Circle Joint Venture and the 333 Market Street Joint Venture, thereby reducing Columbia Property Trust's equity interest in each joint venture to 55.0% . Columbia Property Trust has determined that each of the joint ventures do not qualify as variable interest entities. However, Columbia Property Trust and its partners have substantive participation rights in the joint ventures, including management selection and termination, and the approval of operating and capital decisions. As such, Columbia Property Trust uses the equity method of accounting to record its investment in these joint ventures. Under the equity method, the investment in the joint ventures is recorded at cost and adjusted for cash contributions and distributions, and allocations of income or loss. Columbia Property Trust evaluates the recoverability of its investment in unconsolidated joint ventures in accordance with accounting standards for equity investments by first reviewing the investment for any indicators of impairment. If indicators are present, Columbia Property Trust estimates the fair value of the investment. If the carrying value of the investment is greater than the estimated fair value, management makes an assessment of whether the impairment is "other-than-temporary." In making this assessment, management considers the following: (1) the length of time and the extent to which fair value has been less than cost, and (2) Columbia Property Trust's intent and ability to retain its interest long enough for a recovery in market value. Based on the assessment as described above, Columbia Property Trust has determined that none of its investments in joint ventures are other-than-temporarily impaired as of December 31, 2017 . Mortgage Debt and Related Guaranty The Market Square Joint Venture is the only joint venture with mortgage debt. As of December 31, 2017 and December 31, 2016 , the outstanding balance on the interest-only Market Square mortgage note is $325.0 million , bearing interest at 5.07% . The Market Square mortgage note matures on July 1, 2023. Columbia Property Trust guarantees a portion of the Market Square mortgage note, the amount of which has been reduced to $11.2 million as of December 31, 2017 from $16.1 million as of December 31, 2016 , as a result of leasing at the property. The amount of the guaranty will continue to be reduced as space is leased. Condensed Combined Financial Information Summarized balance sheet information for each of the unconsolidated joint ventures is as follows (in thousands): Total Assets Total Debt Total Equity (1) December 31, 2017 December 31, 2016 December 31, 2017 December 31, 2016 December 31, 2017 December 31, 2016 Market Square Joint Venture $ 590,115 $ 587,344 $ 324,708 $ 324,656 $ 244,506 $ 242,802 University Circle Joint Venture 227,368 — — — 221,154 — 333 Market Street Joint Venture 385,297 — — — 368,994 — 114 Fifth Avenue Joint Venture 392,486 — — — 170,525 — 1800 M Street Joint Venture 458,964 — — — 438,227 — $ 2,054,230 $ 587,344 $ 324,708 $ 324,656 $ 1,443,406 $ 242,802 (1) There is an aggregate basis difference of $32.0 million , which represents the differences between the historical costs recorded at the joint venture level, and Columbia Property Trust's investment in the joint ventures and results from differences in the timing of each partner's interest acquisition and formation costs incurred by Columbia Property Trust. The basis difference is being amortized to income (loss) from unconsolidated joint ventures over the lives of the related assets or liabilities. Summarized income statement information for the unconsolidated joint ventures for the years ended December 31, 2017 , 2016 and 2015 is as follows (in thousands): Total Revenues Net Income (Loss) Columbia Property Trust's Share of Net Income (Loss) 2017 2016 2015 2017 2016 2015 2017 2016 2015 Market Square Joint Venture $ 41,749 $ 41,230 $ 7,962 $ (15,192 ) $ (14,825 ) $ (2,239 ) $ (7,747 ) $ (7,561 ) $ (1,142 ) University Circle Joint Venture 19,386 — — 9,826 — — 7,561 — — 333 Market Street Joint Venture 12,971 — — 6,948 — — 5,331 — — 114 Fifth Avenue Joint Venture 20,133 — — (4,885 ) — — (2,820 ) — — 1800 M Street Joint Venture 8,005 — — 619 — — 326 — — $ 102,244 $ 41,230 $ 7,962 $ (2,684 ) $ (14,825 ) $ (2,239 ) $ 2,651 $ (7,561 ) $ (1,142 ) Property and Asset Management Fees Columbia Property Trust provides property and asset management services to the Market Square Joint Venture, the University Circle Joint Venture , the 333 Market Street Joint Venture, and the 1800 M Street Joint Venture. Under these agreements, Columbia Property Trust oversees the day-to-day operations of these joint ventures and their properties, including property management, property accounting, and other administrative services. During the years ended December 31, 2017 , 2016 , and 2015 , Columbia Property Trust earned the following fees from these unconsolidated joint ventures: 2017 2016 2015 Market Square Joint Venture $ 1,998 $ 2,122 $ 213 University Circle Joint Venture 1,000 — — 333 Market Street Joint Venture 367 — — 1800 M Street Joint Venture 417 — — $ 3,782 $ 2,122 $ 213 Columbia Property Trust also received reimbursements of property operating costs of $2.0 million and $0.5 million for the years ended December 31, 2017 and 2016 , respectively, and none for the year ended December 31, 2015 , which are included in other property income revenues in the accompanying consolidated statements of operations. Property management fees of $0.4 million , and $0.1 million , respectively, were due to Columbia Property Trust from the joint ventures and are included in prepaid expenses and other assets on the accompanying consolidated balance sheets as of December 31, 2017 and December 31, 2016 , respectively.

Line of Credit and Notes Payabl

Line of Credit and Notes Payable	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Line of Credit and Notes Payable	Line of Credit and Notes Payable As of December 31, 2017 and 2016 , Columbia Property Trust had the following line of credit and notes payable indebtedness outstanding (excluding bonds payable; see Note 6, Bonds Payable ) in thousands: Rate as of Term Debt or Interest Only Outstanding Balance as of December 31, Facility Maturity 2017 2016 $300 Million Term Loan LIBOR + 110 bp (1) Interest only 7/31/2020 $ 300,000 $ 300,000 $300 Million Bridge Loan LIBOR + 110 bp (2) Interest only 11/27/2018 300,000 — Revolving Credit Facility LIBOR + 100 bp (3) Interest only 7/31/2019 152,000 — $150 Million Term Loan LIBOR + 110 bp (4) Interest only 7/29/2022 150,000 150,000 263 Shuman Boulevard Building mortgage note (5) 10.55 % Interest only 7/1/2017 49,000 49,000 One Glenlake Building mortgage note 5.80 % Term debt 12/10/2018 23,176 26,315 650 California Street Building mortgage note 3.60 % Term debt 7/1/2019 — 126,287 221 Main Building mortgage note 3.95 % Interest only 5/10/2017 — 73,000 Less: Deferred financing costs related to term loans, bridge loan, and mortgage notes payable (2,991 ) (3,136 ) Total indebtedness $ 971,185 $ 721,466 (1) The $300 Million Term Loan bears interest, at Columbia Property Trust's option, at LIBOR, plus an applicable margin ranging from 0.90% to 1.75% for LIBOR loans, or an alternate base rate, plus an applicable margin ranging from 0.00% to 0.75% for base-rate loans, based on Columbia Property Trust's applicable credit rating. (2) The $300 Million Bridge Loan bears interest, at Columbia Property Trust's option, at LIBOR, plus an applicable margin ranging from 0.90% to 1.75% for LIBOR loans, or an alternate base rate, plus an applicable margin ranging from 0.00% to 0.75% for base-rate loans, based on Columbia Property Trust's applicable credit rating. (3) Borrowings under the Revolving Credit Facility, as described below, bear interest at the option of Columbia Property Trust at LIBOR, plus an applicable margin ranging from 0.875% to 1.55% for LIBOR-based borrowings, or an alternate base rate, plus an applicable margin ranging from 0.00% to 0.55% for base-rate borrowings, based on Columbia Property Trust's applicable credit rating. (4) Columbia Property Trust is party to an interest rate swap agreement with a notional amount of $150.0 million , which effectively fixes its interest rate on the $150 Million Term Loan, as further described below, at 3.07% and terminates on July 29, 2022. This interest rate swap agreement qualifies for hedge accounting treatment; therefore, changes in the fair value are recorded as a market value adjustment to interest rate swap in the accompanying consolidated statement of other comprehensive income. (5) The OfficeMax lease at 263 Shuman Boulevard expired in May 2017, and the mortgage note matured in July 2017. Columbia Property Trust is working with the special-servicer to effect the transfer of the property to the lender in settlement of the loan principal, accrued interest expense and accrued property operating expenses. In the third and fourth quarters of 2017, Columbia Property Trust accrued related interest expense of $2.6 million at the default rate of 10.55% , and property operating expenses of $0.9 million , primarily related to property taxes and repairs and maintenance. $300 Million Bridge Loan On November 27, 2017, Columbia Property Trust entered into a $300.0 million , one -year, unsecured loan with a syndicate of banks led by JPMorgan Chase Bank, N.A. (the " $300 Million Bridge Loan"). The proceeds from the $300 Million Bridge were used to repay borrowings under the Revolving Credit Facility, which were used to fund real estate acquisitions. At Columbia Property Trust's option, borrowings under the $300 Million Bridge Loan bear interest at either (i) an alternate base rate, plus an applicable margin based on five stated pricing levels ranging from 0.00% to 0.75% or (ii) LIBOR, plus an applicable margin based on five stated pricing levels ranging from 0.90% to 1.75% , in each case based on Columbia Property Trust's credit rating. The $300 Million Bridge Loan provides for one six -month extension option to May 24, 2019, subject to certain fees and the satisfaction of certain other conditions. Term Loan Amendment On July 25, 2017, Columbia Property Trust amended the terms of its $150 Million Term Loan, to reduce the current interest rate from 3.52% to 3.07% per annum. The amendment reduced the interest rate from LIBOR, plus an applicable margin ranging from 1.40% to 2.35% , to LIBOR, plus an applicable margin ranging from 0.90% to 1.75% . The maturity date, debt covenants, and other terms of the $150 Million Term Loan are unchanged. The interest rate is effectively fixed with an interest rate swap agreement, which is designated as a cash flow hedge. Debt Covenants The $300 Million Term Loan, the $300 Million Bridge Loan, the $150 Million Term Loan, and the Revolving Credit Facility (collectively, the "Debt Facilities") contain representations and warranties, financial and other affirmative and negative covenants, events of defaults, and remedies typical for these types of facilities. The financial covenants in the Debt Facilities: (a) limit the ratio of secured debt to total asset value, as defined therein, to 40% or less; (b) require the fixed charge coverage ratio, as defined therein, to be at least 1.50 :1.00; (c) limit the ratio of debt to total asset value, as defined therein, to 60% or less; (d) require the ratio of unencumbered adjusted net operating income, as defined therein, to unsecured interest expense, as defined therein, to be at least 1.75 :1.00; (e) require the ratio of unencumbered asset value, as defined therein, to total unsecured debt, as defined therein, to be at least 1.66 :1.00; and (f) require maintenance of certain minimum tangible net worth balances. As of December 31, 2017 , Columbia Property Trust believes it was in compliance with the restrictive financial covenants on its Debt Facilities and notes payable obligations. Fair Value of Debt The estimated fair value of Columbia Property Trust's consolidated line of credit and notes payable as of December 31, 2017 and 2016 , was approximately $975.3 million and $728.5 million , respectively. The related carrying value of the line of credit and notes payable as of December 31, 2017 and 2016 , was $974.2 million and $724.6 million , respectively. Columbia Property Trust estimated the fair value of its line of credit by obtaining estimates for similar facilities from multiple market participants as of the respective reporting dates. Therefore, the fair values determined are considered to be based on observable market data for similar instruments (Level 2). The fair values of all other debt instruments were estimated based on discounted cash flow analyses using the current incremental borrowing rates for similar types of borrowing arrangements as of the respective reporting dates (Level 3). Interest Paid and Capitalized As of December 31, 2017 and 2016 , Columbia Property Trust's weighted-average interest rate on its consolidated line of credit and notes payable was approximately 3.16% and 3.09% , respectively. Columbia Property Trust made interest payments of approximately $21.5 million , $27.8 million , and $54.0 million during 2017 , 2016 , and 2015 , respectively, of which approximately $0.7 million , $0.3 million , and $0.6 million was capitalized during 2017 , 2016 , and 2015 , respectively. Debt Repayments and Maturities During 2017 and 2016 Columbia Property Trust made the following debt repayments: • On August 17, 2017, Columbia Property Trust repaid the $124.8 million balance of the 650 California Street building mortgage note, which was originally scheduled to mature on July 1, 2019. Columbia Property Trust recognized a loss on early extinguishment of debt of $0.3 million related to unamortized deferred financing costs. • On March 10, 2017, Columbia Property Trust repaid the $73.0 million balance of the 221 Main Street building mortgage note, which was originally scheduled to mature on May 10, 2017. Columbia Property Trust recognized a loss on early extinguishment of debt of $45,000 related to unamortized deferred financing costs. • On October 3, 2016, a portion of the proceeds from the sale of the 80 Park Plaza Property was used to repay the $99.0 million remaining outstanding balance on the Revolving Credit Facility. • On June 30, 2016, Columbia Property Trust used borrowings on the Revolving Credit Facility to repay the $39.0 million SanTan Corporate Center mortgage notes, which were scheduled to mature on October 11, 2016. Columbia Property Trust recognized a loss on early extinguishment of debt of $10,000 related to unamortized deferred financing costs. • On April 1, 2016, Columbia Property Trust repaid the $119.0 million remaining on the 2015 Bridge Loan, which was used to finance a portion of the 229 West 43rd Street Building acquisition in August of 2015. The 2015 Bridge Loan was scheduled to mature on August 4, 2016. Columbia Property Trust recognized a loss on early extinguishment of debt of $82,000 related to unamortized deferred financing costs. The following table summarizes the aggregate maturities of Columbia Property Trust's line of credit and notes payable as of December 31, 2017 (in thousands): 2018 $ 323,176 2019 152,000 2020 300,000 2021 — 2022 150,000 Thereafter — Total (1) $ 925,176 (1) The $49.0 million 263 Shuman mortgage note is excluded from this table. The mortgage note matured in July 2017. Columbia Property Trust is working with the special-servicer to effect the transfer of the property to the lender in settlement of the loan principal, accrued interest expense, and accrued property operating expenses.

Bonds Payable

Bonds Payable	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Bonds Payable	Bonds Payable On August 12, 2016, Columbia Property Trust OP issued $350 million of 10 -year, unsecured 3.650% senior notes, which are guaranteed by Columbia Property Trust, at 99.626% of its face value (the "2026 Bonds Payable"), pursuant to a shelf registration statement. Columbia Property Trust OP received net proceeds from the 2026 Bonds Payable of $346.4 million , which were used to redeem $250.0 million of seven -year, unsecured 5.875% senior notes due April 2018 (the "2018 Bonds Payable"). The 2026 Bonds Payable require semi-annual interest payments in February and August based on a contractual annual interest rate of 3.650% . In the accompanying consolidated balance sheets, the 2026 Bonds Payable are shown net of the initial issuance discount of approximately $1.3 million , which will be amortized to interest expense over the term of the 2026 Bonds Payable using the effective interest method. The principal amount of the 2026 Bonds Payable is due and payable on the maturity date, August 15, 2026. In March 2015, Columbia Property Trust OP issued $350.0 million of 10 -year, unsecured 4.150% senior notes, which are guaranteed by Columbia Property Trust, at 99.859% of their face value (the "2025 Bonds Payable"), pursuant to a shelf registration statement. Columbia Property Trust OP received proceeds from the 2025 Bonds Payable, net of fees, of $347.2 million . The 2025 Bonds Payable require semi-annual interest payments in April and October based on a contractual annual interest rate of 4.150% . In the accompanying consolidated balance sheets, the 2025 Bonds Payable are shown net of the initial issuance discount of approximately $0.5 million , which will be amortized to interest expense over the term of the 2025 Bonds Payable using the effective interest method. The principal amount of the 2025 Bonds Payable is due and payable on the maturity date, April 1, 2025. During the year ended December 31, 2017 , Columbia Property Trust made interest payments of $27.4 million on the 2025 Bonds Payable and 2026 Bonds Payable; and during the year ended December 31, 2016 , Columbia Property Trust made interest payments of $28.0 million on the 2025 Bonds Payable and the 2018 Bonds Payable. Interest payments on the 2026 Bonds Payable began in February 2017. The restrictive covenants on the 2026 Bonds Payable and the 2025 Bonds Payable, as defined, pursuant to an indenture include: • a limitation on the ratio of debt to total assets, as defined, to 60% ; • limits to Columbia Property Trust's ability to incur debt if the consolidated income available for debt service to annual debt service charge, as defined, for four previous consecutive fiscal quarters is less than 1.5:1 on a pro forma basis; • limits to Columbia Property Trust's ability to incur liens if, on an aggregate basis for Columbia Property Trust, the secured debt amount would exceed 40% of the value of the total assets; and • a requirement that the ratio of unencumbered asset value, as defined, to total unsecured debt be at least 150% at all times. As of December 31, 2017 , Columbia Property Trust believes it was in compliance with the restrictive financial covenants on its 2026 Bonds Payable and 2025 Bonds Payable. The estimated fair value of the 2025 Bonds Payable and the 2026 Bonds Payable as of December 31, 2017 and 2016 , was approximately $702.8 million and $703.1 million , respectively. The related carrying value of the bonds payable, net of discounts, as of December 31, 2017 and 2016 , was $698.5 million and $698.3 million , respectively. The fair value of the bonds payable was estimated based on discounted cash flow analyses using the current incremental borrowing rates for similar types of borrowing as of the respective reporting dates (Level 2). The discounted cash flow method of assessing fair value results in a general approximation of value, which may differ from the price that could be achieved in a market transaction.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments Under Existing Lease Agreements Certain lease agreements include provisions that, at the option of the tenant, may obligate Columbia Property Trust to expend capital to expand an existing property or provide other expenditures for the benefit of the tenant. As of December 31, 2017 , no tenants have exercised such options that have not been materially satisfied or recorded as a liability in the accompanying consolidated balance sheets. Obligations Under Operating Leases Columbia Property Trust owns three properties that are subject to ground leases with expiration dates of February 28, 2062 , December 14, 2077, and July 31, 2099 , respectively. The lease expiring on December 14, 2077, has been fully prepaid. Columbia Property Trust also leases space for its corporate office. Columbia Property Trust incurred $2.6 million in rent expense related to such leases in 2017 , 2016 , and 2015 . As of December 31, 2017 , the required payments under the terms of the remaining two consolidated ground leases and the corporate office lease are as follows (in thousands): 2018 $ 3,282 2019 3,360 2020 3,382 2021 3,405 2022 3,587 Thereafter 192,352 Total $ 209,368 Obligations Under Capital Leases The building at Three Glenlake is subject to a capital lease of land. This obligation requires payments equal to the amounts of principal and interest receivable from related investments in development authority bonds, which mature in 2021 . The required payments under the terms of the leases are as follows as of December 31, 2017 (in thousands): 2018 $ 7,200 2019 7,200 2020 7,200 2021 127,200 2022 — Thereafter — 148,800 Amounts representing interest (28,800 ) Total $ 120,000 Guaranty of Debt of Unconsolidated Joint Venture Upon entering into the Market Square Joint Venture in October 2015, Columbia Property Trust entered into a guaranty of a $25.0 million portion of the Market Square mortgage note, the amount of which is reduced as space is leased. As a result of leasing, the guaranty has been reduced to $11.2 million as of December 31, 2017 . Columbia Property Trust believes that the likelihood of making a payment under this guaranty is remote; therefore, no liability has been recorded related to this guaranty as of December 31, 2017 . Litigation Columbia Property Trust is subject to various legal proceedings, claims, and administrative proceedings arising in the ordinary course of business, some of which are expected to be covered by liability insurance. Management makes assumptions and estimates concerning the likelihood and amount of any reasonably possible loss relating to these matters using the latest information available. Columbia Property Trust records a liability for litigation if an unfavorable outcome is probable and the amount of loss or range of loss can be reasonably estimated. If an unfavorable outcome is probable and a reasonable estimate of the loss is a range, Columbia Property Trust accrues the best estimate within the range. If no amount within the range is a better estimate than any other amount, Columbia Property Trust accrues the minimum amount within the range. If an unfavorable outcome is probable but the amount of the loss cannot be reasonably estimated, Columbia Property Trust discloses the nature of the litigation and indicates that an estimate of the loss or range of loss cannot be made. If an unfavorable outcome is reasonably possible and the estimated loss is material, Columbia Property Trust discloses the nature and estimate of the possible loss of the litigation. Columbia Property Trust does not disclose information with respect to litigation where the possibility of an unfavorable outcome is considered to be remote. Based on current expectations, such matters, both individually and in the aggregate, are not expected to have a material adverse effect on the liquidity, results of operations, business, or financial condition of Columbia Property Trust. Columbia Property Trust is not currently involved in any legal proceedings of which management would consider the outcome to be reasonably likely to have a material adverse effect on the results of operations or financial condition of Columbia Property Trust.

Equity

Equity	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity	Equity Common Stock Repurchase Program Columbia Property Trust's board of directors authorized the repurchase of up to an aggregate of $200.0 million of its common stock, par value $0.01 per share, from September 4, 2015 through September 4, 2017 (the "2015 Stock Repurchase Program"). Under the 2015 Stock Repurchase Program, Columbia Property Trust acquired 5.6 million shares at an average price of $21.85 per share, for aggregate purchases of $121.4 million . Columbia Property Trust's board of directors authorized a second stock repurchase program to purchase up to an aggregate of $200.0 million of its common stock, par value $0.01 per share, from September 4, 2017 through September 4, 2019 (the "2017 Stock Repurchase Program"). During the year ended December 31, 2017 , Columbia Property Trust repurchased 2.7 million shares at an average price of $21.46 per share, for aggregate purchases of $57.6 million under the 2015 Stock Repurchase Program and the 2017 Stock Repurchase Program. As of December 31, 2017 , $194.8 million remains available for repurchases under the 2017 Stock Repurchase Program. Common stock repurchases are charged against equity as incurred, and the repurchased shares are retired. Columbia Property Trust will continue to evaluate the purchase of shares, primarily through open market transactions, which are subject to market conditions and other factors. Long-Term Incentive Plan Columbia Property Trust maintains a shareholder-approved, long-term incentive plan that provides for grants of stock to be made to certain employees and independent directors of Columbia Property Trust (as amended and restated, the "LTIP"). In May 2017, Columbia Property Trust's shareholders approved the LTIP, and 4.8 million shares are authorized and reserved for issuance under the LTIP. On January 20, 2017, Columbia Property Trust granted 193,535 shares of common stock to employees, net of 17,938 shares withheld to settle the related tax liability, under the LTIP for 2016 performance, of which 25% vested upon grant; the remaining shares will vest ratably, with the passage of time, on January 31, 2018, 2019, and 2020. Employees receive quarterly dividends related to their entire grant, including the unvested shares, on each dividend payment date. For 2017, Columbia Property Trust modified the structure of awards granted under the LTIP to include both time-based awards and performance-based awards for all participants. For the 2017 time-based awards, Columbia Property Trust issued 139,825 shares of common stock to employees, which will vest ratably on each anniversary of the grant date over the next four years. For the 2017 performance-based awards, Columbia Property Trust granted 193,219 restricted share units (the "Performance-Based RSUs"), of which 75% will vest at the conclusion of a three -year performance period, and the remaining 25% will vest one year later. In addition, Columbia Property Trust granted 45,076 and 92,585 one-time transitional Performance-Based RSUs, which will fully vest at the conclusion of one -year and two -year performance periods, respectively. Upon reaching a predefined performance threshold, the payout of the Performance-Based RSUs will range from 50% to 150% of the Performance-Based RSUs granted, depending on Columbia Property Trust’s total stockholder return relative to the FTSE NAREIT Equity Office Index. All awards are expensed over the vesting period based on their estimated fair values. The fair-value of time-based awards is estimated using the closing stock price on the grant date; and fair values of performance-based awards are estimated using a Monte Carlo valuation method. The 2018 LTIP awards are consistent with the 2017 LTIP awards. On January 1, 2018, Columbia Property Trust granted 128,486 shares of time-based stock awards to employees, which will vest ratably on each anniversary of the grant over the next four years. On January 1, 2018, Columbia Property Trust granted 176,702 Performance-Based RSUs, of which 75% will vest at the conclusion of a three -year performance period, and the remaining 25% will vest one year later. Consistent with the 2017 plan, the payout of the 2018 Performance-Based RSUs will be determined based on Columbia Property Trust’s total shareholder return relative to the FTSE NAREIT Equity Office Index. Below is a summary of the shares of stock issued under the LTIP for the years ended December 31, 2017, 2016, and 2015: Shares (in thousands) Weighted-Average, Grant-Date Fair Value (1) Unvested shares as of January 1, 2015 104 $ 24.82 Granted 123 $ 24.40 Vested (74 ) $ 24.60 Forfeited (2 ) $ 24.56 Unvested shares as of December 31, 2015 151 $ 24.59 Granted 247 $ 21.79 Vested (138 ) $ 23.32 Forfeited (4 ) $ 21.90 Unvested shares as of December 31, 2016 256 $ 22.62 Granted 333 $ 21.59 Vested (193 ) $ 22.42 Forfeited (7 ) $ 21.81 Unvested shares as of December 31, 2017 389 (2) $ 21.85 (1) Columbia Property Trust determined the weighted-average grant-date fair value using the market closing price on the date of the grant. (2) As of December 31, 2017 , Columbia Property Trust expects approximately 370,000 of the 389,000 unvested shares to ultimately vest, assuming a forfeiture rate of 5% , which was determined based on peer company data, adjusted for the specifics of the LTIP. A summary of the activity for the Performance-Based RSUs under the LTIP follows: Performance-Based RSU Awards (in thousands) Weighted-Average, Grant-Date Fair Value (1) Unvested performance-based share awards as of December 31, 2016 — $ — Granted 331 $ 18.78 Vested — $ — Forfeited (2 ) $ 19.01 Unvested performance-based share awards as of December 31, 2017 329 (2) $ 18.78 (1) Columbia Property Trust determined the weighted-average grant-date fair value using the estimated fair value on the date of grant. (2) As of December 31, 2017 , Columbia Property Trust expects approximately 303,000 of the 329,000 unvested performance-based restricted share units to ultimately vest, assuming a forfeiture rate of 8% , which was determined based on peer company data, adjusted for the specifics of the LTIP. Director Stock Grants In May 2017, Columbia Property Trust began paying its directors' equity retainers on an annual basis for the ensuing period. From January 2014 through January 3, 2017, Columbia Property Trust paid these equity retainers in quarterly installments. The equity retainers vest at the time of grant. A summary of these grants, made under the LTIP, follows: Date of Grant Shares Weighted-Average Grant-Date Fair Value 2017 Director Grants: January 3, 2017 8,279 $ 21.58 May 2, 2017 33,581 $ 22.57 November 27, 2017 (1) 1,596 $ 23.07 2016 Director Grants: January 4, 2016 7,439 $ 23.00 April 1, 2016 8,120 $ 21.89 July 1, 2016 8,158 $ 21.52 October 3, 2016 7,727 $ 22.19 2015 Director Grants: January 2, 2015 5,850 $ 25.75 April 1, 2015 4,995 $ 27.16 July 1, 2015 4,144 $ 24.84 October 1, 2015 4,571 $ 23.40 (1) In November 2017, a new director was appointed to the board of directors of Columbia Property Trust. The new director received a pro-rated annual equity retainer grant at appointment. Stock-Based Compensation Expense Columbia Property Trust incurred stock-based compensation expense related to the following events (in thousands): 2017 2016 2015 Amortization of unvested LTIP awards $ 4,098 $ 2,856 $ 1,699 Future employee awards (1) 2,509 1,006 1,353 Issuance of shares to independent directors 973 696 496 Total stock-based compensation expense $ 7,580 $ 4,558 $ 3,548 (1) Reflects amortization of LTIP awards for service during the current period, for which shares will be issued in future periods. These expenses are included in general and administrative expenses in the accompanying consolidated statements of operations. There were $8.1 million and $3.2 million of unrecognized compensation costs related to unvested awards under the LTIP as of December 31, 2017 and December 31, 2016 , respectively. This amount will be amortized over the respective vesting period, ranging from one year to four years at the time of grant. Effective in 2017, Columbia Property Trust changed from an LTIP measured over a one -year performance period to an LTIP measured over a three -year performance period and, as a result, has issued additional unvested shares in 2017. Independent Director Stock Option Plan Columbia Property Trust previously maintained an independent director stock option plan that provides for grants of stock to be made to independent directors of Columbia Property Trust (the "Director Plan"). A total of 25,000 shares were authorized and reserved for issuance under the Director Plan, which was suspended in April of 2008. Under the Director Plan, options were granted upon appointment to the board and on each annual meeting date. All options granted under the Director Plan have expired. A summary of stock option activity under the Director Plan during 2017 , 2016 , and 2015 , follows: Number Exercise Price Exercisable Outstanding as of December 31, 2014 3,875 $ 48.00 3,875 Granted — Expired (2,000 ) Outstanding as of December 31, 2015 1,875 $ 48.00 1,875 Granted — Expired (500 ) Outstanding as of December 31, 2016 1,375 $ 48.00 1,375 Granted — Expired (1,375 ) Outstanding as of December 31, 2017 — $ — — Columbia Property Trust has evaluated the fair values of options granted under the Director Plan using the Black-Scholes-Merton model and concluded that such values are insignificant as of the end of the period presented.

Operating Leases

Operating Leases	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Operating Leases	Operating Leases Columbia Property Trust's real estate assets are leased to tenants under operating leases for which the terms vary, including certain provisions to extend the lease agreement, options for early terminations, subject to specified penalties, and other terms and conditions as negotiated. Columbia Property Trust retains substantially all of the risks and benefits of ownership of the real estate assets leased to tenants. Amounts required as security deposits vary depending upon the terms of the respective leases and the creditworthiness of the tenant; however, such deposits generally are not significant. Therefore, exposure to credit risk exists to the extent that the receivables exceed this amount. Security deposits related to tenant leases are included in accounts payable, accrued expenses, and accrued capital expenditures in the accompanying consolidated balance sheets. Based on 2017 annualized lease revenue, as defined, none of Columbia Property Trust's tenants represent more than 6% of Columbia Property Trust's portfolio. Tenants in business services, depository institutions, and engineering and management services represent 23% , 11% , and 8% , respectively, of Columbia Property Trust's annualized lease revenue. Columbia Property Trust's properties are located primarily in New York, San Francisco, Washington, D.C., and Atlanta. As of December 31, 2017 , approximately 38% , 28% , and 14% of Columbia Property Trust's office properties are located in New York, San Francisco, and Washington, D.C., respectively, based on annualized lease revenue. The future minimum rental income from Columbia Property Trust's investment in real estate assets under noncancelable operating leases, excluding lease incentives, as of December 31, 2017 , is as follows (in thousands): 2018 $ 231,641 2019 247,774 2020 243,053 2021 207,919 2022 192,322 Thereafter 1,440,917 Total $ 2,563,626 As of December 31, 2017 , Columbia Property Trust has recognized lease incentive obligations of $66.3 million , which will be amortized against rental income over the 30 -year life of the related lease.

Supplemental Disclosures of Non

Supplemental Disclosures of Noncash Investing and Financing Activities	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosures of Noncash Investing and Financing Activities	Supplemental Disclosures of Noncash Investing and Financing Activities Outlined below are significant noncash investing and financing activities for the years ended December 31, 2017 , 2016 , and 2015 (in thousands): Years Ended December 31, 2017 2016 2015 Investment in real estate funded with other assets $ 311 $ 1,442 $ 27,000 Deposits applied to sales of real estate $ 10,000 $ — $ — Other assets assumed upon acquisition $ 1,014 $ — $ 7,785 Other liabilities assumed upon acquisition $ 268 $ — $ 4,765 Real estate assets transferred to unconsolidated joint venture $ 558,122 $ — $ 531,696 Mortgage note transferred to unconsolidated joint venture $ — $ — $ 325,000 Other assets transferred to unconsolidated joint venture $ 43,700 $ — $ 37,987 Other liabilities transferred to unconsolidated joint venture $ 21,347 $ — $ 20,595 Discount on issuance of bonds payable $ — $ 1,309 $ 494 Amortization of discounts (premiums) on debt $ 180 $ 267 $ (18 ) Market value adjustment to interest rate swaps that qualify for hedge accounting treatment $ 1,786 $ 1,553 $ (1,570 ) Accrued capital expenditures and deferred lease costs $ 25,069 $ 15,042 $ 19,324 Accrued dividends payable $ 23,961 $ 36,727 $ 37,354 Common stock issued to employees and directors, and amortized (net of income tax witholdings) $ 5,764 $ 3,388 $ 3,548

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Columbia Property Trust's income tax basis net income during 2017 , 2016 , and 2015 (in thousands) follows: 2017 2016 2015 GAAP basis financial statement net income attributable to the common stockholders of Columbia Property Trust, Inc. $ 176,041 $ 84,281 $ 44,619 Increase (Decrease) in Net Income Resulting From: Depreciation and amortization expense for financial reporting purposes in excess of amounts for income tax purposes 33,918 34,569 81,559 Rental income accrued for financial reporting purposes in excess of amounts for income tax purposes (38,426 ) (26,900 ) (13,409 ) Net amortization of above-/below-market lease intangibles for financial reporting purposes less than amounts for income tax purposes (6,091 ) (9,013 ) (6,626 ) Gain on interest rate swaps that do not qualify for hedge accounting treatment for financial reporting purposes in excess of amounts for income tax purposes — — (2,633 ) Bad debt expense for financial reporting purposes less than amounts for income tax purposes (31 ) (261 ) 5 Income from unconsolidated joint ventures for financial reporting purchases in excess of amount for income tax purposes 13,902 — — Gains or losses on disposition of real property for financial reporting purposes that are more favorable than amounts for income tax purposes (126,770 ) (71,701 ) (117,857 ) Other expenses for financial reporting purposes in excess of amounts for income tax purposes 11,331 (2,707 ) 14,342 Income tax basis net income, prior to dividends-paid deduction $ 63,874 $ 8,268 $ — As of December 31, 2017 , the tax basis carrying value of Columbia Property Trust's total assets was approximately $4.6 billion . For income tax purposes, distributions to common stockholders are characterized as ordinary income, capital gains, or as a return of a stockholder's invested capital. Columbia Property Trust's distributions per common share are summarized as follows: 2017 2016 2015 Ordinary income 58.5 % 5.6 % — % Capital gains — % — % — % Return of capital 41.5 % 94.4 % 100.0 % Total 100.0 % 100.0 % 100.0 % As of December 31, 2017 , returns for the calendar years 2013 through 2017 remain subject to examination by U.S. or various state tax jurisdictions. No provisions for federal income taxes have been made in the accompanying consolidated financial statements, other than the provisions relating to the TRS Entities, as Columbia Property Trust made distributions in excess of taxable income for the periods presented. Columbia Property Trust is subject to certain state and local taxes related to property operations in certain locations, which have been provided for in the accompanying consolidated financial statements. The income taxes recorded by the TRS Entities for the years ended December 31, 2017 , 2016 , and 2015 , are as follows: Years Ended December 31, 2017 2016 2015 Federal income tax $ 188 $ 255 $ 17 State income tax 38 21 25 Total income tax $ 226 $ 276 $ 42 As of December 31, 2017 , Columbia Property Trust had a deferred tax asset of $205,000 , and as of December 31, 2016 , Columbia Property Trust had a deferred tax liability of $ 22,000 , which are included in prepaid expenses and other assets in the accompanying consolidated balance sheets.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The basic and diluted earnings-per-share computations and net income have been reduced for the dividends paid on unvested shares related to the LTIP grants, as described in Note 8, Equity . The following table reconciles the numerator for the basic and diluted earnings-per-share computations shown on the consolidated statements of income (in thousands): 2017 2016 2015 Net income $ 176,041 $ 84,281 $ 44,619 Distributions paid on unvested shares (337 ) (314 ) (185 ) Net income used to calculate basic and diluted earnings per share $ 175,704 $ 83,967 $ 44,434 The following table reconciles the denominator for the basic and diluted earnings-per-share computations shown on the consolidated statements of income (in thousands): 2017 2016 2015 Weighted-average common shares – basic 120,795 123,130 124,757 Plus Incremental Weighted-Average Shares From Time-Vested Conversions Less Assumed Share Repurchases: Previously granted LTIP awards, unvested 116 58 33 Future LTIP awards 248 40 57 Weighted-average common shares – diluted 121,159 123,228 124,847

Quarterly Results (Unaudited)

Quarterly Results (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Results (Unaudited)	Quarterly Results (Unaudited) Presented below is a summary of the unaudited quarterly financial information for the years ended December 31, 2017 and 2016 (in thousands, except per-share data): 2017 First Quarter Second Quarter Third Quarter Fourth Quarter Revenues $ 82,156 $ 74,857 $ 60,362 $ 71,625 Net income $ 74,722 (1) $ 1,133 $ 101,534 (2) $ (1,348 ) Net income per share – basic $ 0.61 $ 0.01 $ 0.84 $ (0.01 ) Net income per share – diluted $ 0.61 $ 0.01 $ 0.84 $ (0.01 ) Dividends declared per share $ 0.20 $ 0.20 $ 0.20 $ 0.20 2016 First Quarter Second Quarter Third Quarter Fourth Quarter Revenues $ 126,579 $ 127,930 $ 113,266 $ 105,768 Net income $ 6,697 $ 13,286 (3) $ 36,898 (4) $ 27,400 (5) Net income per share – basic $ 0.05 $ 0.11 $ 0.30 $ 0.22 Net income per share – diluted $ 0.05 $ 0.11 $ 0.30 $ 0.22 Dividends declared per share $ 0.30 $ 0.30 $ 0.30 $ 0.30 (1) Net income for the first quarter of 2017 includes gains on sales of real estate assets of $73.2 million related to the sales of real estate assets as described in Note 3, Real Estate Transactions . (2) Net income for the third quarter of 2017 includes gains on sales of real estate assets of $102.4 million related to the sales of real estate assets as described in Note 3, Real Estate Transactions . (3) Net income for the second quarter of 2016 includes an early termination payment at 222 East 41st Street of $6.2 million . (4) Net income for the third quarter of 2016 includes gains on sales of real estate assets of $50.4 million related to the sales of real estate assets as described in Note 3, Real Estate Transactions ; partially offset by losses on early extinguishment of debt of $18.9 million related to the early repayment of the 2018 Bonds Payable. (5) Net income for the fourth quarter of 2016 includes gains on sales of real estate assets of $22.2 million related to the sales of real estate assets as described in Note 3, Real Estate Transactions .

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information Columbia Property Trust establishes operating segments at the property level, and aggregates individual properties into reportable segments for geographic locations in which Columbia Property Trust has significant investments. Columbia Property Trust considers geographic location when evaluating its portfolio composition, and in assessing the ongoing operations and performance of its properties. As of December 31, 2017, Columbia Property Trust had the following reportable segments: New York, San Francisco, Atlanta, Washington, D.C., Boston, Los Angeles, and all other office markets. The all other office markets reportable segment consists of properties in similar low-barrier-to-entry geographic locations in which Columbia Property Trust does not have a substantial presence and does not plan to make further investments. During the periods presented, there have been no material inter-segment transactions. Net operating income ("NOI") is a non-GAAP financial measure and is not considered a measure of operating results or cash flows from operations under GAAP. NOI is the primary performance measure reviewed by management to assess operating performance of properties and is calculated by deducting operating expenses from operating revenues. Operating revenues include rental income, tenant reimbursements, hotel income, and other property income; and operating expenses include property and hotel operating costs. The NOI performance metric consists of only revenues and expenses directly related to real estate rental operations. NOI reflects property acquisitions and dispositions, occupancy levels, rental rate increases or decreases, and the recoverability of operating expenses. NOI, as Columbia Property Trust calculates it, may not be directly comparable to similarly titled, but differently calculated, measures for other REITs. Asset information and capital expenditures by segment are not reported because Columbia Property Trust does not use these measures to assess performance. Depreciation and amortization expense, along with other expense and income items, are not allocated among segments. The following table presents property operating revenues by geographic reportable segment (in thousands): For the Years Ended December 31, 2017 2016 2015 New York (1) $ 123,280 $ 117,235 $ 97,643 San Francisco (2) 105,550 109,995 112,696 Atlanta 37,803 36,742 35,715 Washington, D.C. (3) 36,934 33,024 62,766 Boston 11,559 11,796 20,895 Los Angeles 7,462 7,443 7,588 All other office markets 21,460 152,858 207,367 Total office segments 344,048 469,093 544,670 Hotel 1,328 22,958 24,583 Corporate (4) 579 397 267 Total $ 345,955 $ 492,448 $ 569,520 (1) Includes operating revenues for 49.5% of 114 Fifth Avenue based on Columbia Property Trust's ownership interest, from July 6, 2017 through December 31, 2017. These operating revenues are included in equity in income (loss) of unconsolidated joint ventures in the accompanying consolidated statements of operations. (2) Includes operating revenues for 100.0% of 333 Market Street and University Circle through July 5, 2017. Includes operating revenues for 77.5% of 333 Market Street and University Circle based on Columbia Property Trust's ownership interest, from July 6, 2017 through December 31, 2017, which are included in equity in income (loss) of unconsolidated joint ventures in the accompanying consolidated statements of operations. (3) Includes operating revenues for 100.0% of Market Square through October 28, 2015. Includes operating revenues for 51.0% of the Market Square buildings based on Columbia Property Trust's ownership interest, from October 28, 2015 through December 31, 2017; and includes operating revenues for 55.0% of 1800 M Street based on Columbia Property Trust's ownership interest, from October 11, 2017 through December 31, 2017, which are included in equity in income (loss) of unconsolidated joint ventures in the accompanying consolidated statements of operations. (4) The amounts for 2016 and 2015 have been adjusted to conform with 2017 presentation by removing asset and property management fee income. A reconciliation of GAAP revenues to operating revenues is presented below (in thousands): For the Years Ended December 31, 2017 2016 2015 Total revenues $ 289,000 $ 473,543 $ 566,065 Operating revenues included in income (loss) from unconsolidated joint ventures (1) 60,737 21,027 4,060 Asset and property management fee income (2) (3,782 ) (2,122 ) (605 ) Total property operating revenues $ 345,955 $ 492,448 $ 569,520 (1) Columbia Property Trust records its interest in properties held through unconsolidated joint ventures using the equity method of accounting, and reflects its interest in the operating revenues of these properties in income (loss) from unconsolidated joint ventures in the accompanying consolidated statements of operations. (2) See Note 4, Unconsolidated Joint Ventures , of the accompanying consolidated financial statements. The following table presents net operating income by geographic reportable segment (in thousands): For the Years Ended December 31, 2017 2016 2015 New York (1) $ 73,893 $ 70,038 $ 54,692 San Francisco (2) 76,163 80,529 83,826 Atlanta 33,603 32,939 31,912 Washington, D.C. (3) 18,496 16,372 36,958 Boston 5,380 5,114 12,519 Los Angeles 4,529 4,523 4,853 All other office markets 18,550 92,756 129,199 Total office segments 230,614 302,271 353,959 Hotel (913 ) 3,988 4,593 Corporate (4) (826 ) (158 ) (586 ) Total $ 228,875 $ 306,101 $ 357,966 (1) Includes net operating income for 49.5% of 114 Fifth Avenue based on Columbia Property Trust's ownership interest, from July 6, 2017 through December 31, 2017. This net operating income is included in equity in income (loss) of unconsolidated joint ventures in the accompanying consolidated statements of operations. (2) Includes net operating income for 100.0% of 333 Market Street and University Circle through July 5, 2017. Includes net operating income for 77.5% of 333 Market Street and University Circle based on Columbia Property Trust's ownership interest, from July 6, 2017 through December 31, 2017, which is included in equity in income (loss) of unconsolidated joint ventures in the accompanying consolidated statements of operations. (3) Includes net operating income for 100.0% of Market Square through October 28, 2015. Includes net operating income for 51.0% of the Market Square buildings based on Columbia Property Trust's ownership interest, from October 28, 2015 through December 31, 2017; and includes net operating income for 55.0% of 1800 M Street based on Columbia Property Trust's ownership interest, from October 11, 2017 through December 31, 2017. This net operating income is included in equity in income (loss) of unconsolidated joint ventures in the accompanying consolidated statements of operations. (4) The amounts for 2016 and 2015 have been adjusted to conform with 2017 presentation by removing asset and property management fee income. A reconciliation of GAAP net income to NOI is presented below (in thousands): For the Years Ended December 31, 2017 2016 2015 Net income $ 176,041 $ 84,281 $ 44,619 Depreciation 80,394 108,543 131,490 Amortization 32,403 56,775 87,128 General and administrative – corporate 34,966 33,876 29,683 General and administrative – joint venture 1,454 — — Real estate acquisition costs — — 3,675 Net interest expense 58,187 67,538 85,265 Interest income from development authority bonds (7,200 ) (7,200 ) (7,200 ) Interest rate swap valuation adjustment — — (2,634 ) Interest expense associated with interest rate swap — — 2,642 Settlement of interest rate swap — — 1,102 Loss on early extinguishment of debt 325 18,997 3,149 Income tax expense (213 ) 445 378 Asset and property management fee income (3,782 ) (2,122 ) (605 ) Adjustments included in loss from unconsolidated joint venture 31,818 17,293 3,134 Gains on sales of real estate assets (175,518 ) (72,325 ) (23,860 ) Net operating income $ 228,875 $ 306,101 $ 357,966

Financial Information for Paren

Financial Information for Parent Guarantor, Other Guarantor Subsidiaries, and Non-Guarantor Subsidiaries	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Financial Information for Parent Guarantor, Other Guarantor Subsidiaries, and Non-Guarantor Subsidiaries	Financial Information for Parent Guarantor, Other Guarantor Subsidiaries, and Non-Guarantor Subsidiaries The 2026 Bonds Payable and the 2025 Bonds Payable (see Note 6, Bonds Payable ) were issued by Columbia Property Trust OP, and are guaranteed by Columbia Property Trust. In accordance with SEC Rule 3-10(c), Columbia Property Trust includes herein condensed consolidating financial information in lieu of separate financial statements of the subsidiary issuer (Columbia Property Trust OP), as defined in the bond indentures, because all of the following criteria are met: (1) the subsidiary issuer (Columbia Property Trust OP) is 100% owned by the parent company guarantor (Columbia Property Trust); (2) the guarantees are full and unconditional; and (3) no other subsidiary of the parent company guarantor (Columbia Property Trust) guarantees the 2025 Bonds Payable or the 2018 Bonds Payable. Columbia Property Trust uses the equity method with respect to its investment in subsidiaries included in its condensed consolidating financial statements. Columbia Property Trust has corrected the presentation of intercompany cash transfers between the REIT Parent and its subsidiaries in the consolidating statements of cash flow. Instead of showing one amount for intercompany transfers between each entity group, intercompany transfers are broken out by cash flow type (i.e. operating, investing, and financing) for all periods presented, consistent with the equity method of accounting. All such changes are eliminated in consolidation, and therefore do not impact Columbia Property Trust's consolidated financial statement totals. Management has concluded that the effect of this correction is not material to the consolidated financial statements. This change had the following impact to the condensed consolidating statement of cash flows for the years ended December 31, 2016 : increase to operating cash flows for the parent and issuer of $53.1 million and $136.7 million , respectively; and increase (decrease) in investing cash flows for the parent, issuer, and non-guarantors of $(281.8) million , $568.5 million and $603.7 million , respectively; and increase (decrease) in financing cash flows for the parent, issuer, and non-guarantors of $228.7 million , $(705.2) million , and $(603.7) million , respectively. This change had the following impact to the condensed consolidating statement of cash flows for the years ended December 31, 2015 : increase to operating cash flows for the parent of $15.7 million ; and increase (decrease) in investing cash flows for the parent, issuer, and non-guarantors of $1,045.9 million , $(145.3) million and $(468.0) million , respectively; and increase (decrease) in financing cash flows for the parent, issuer, and non-guarantors of $(1,061.6) million , $145.3 million and $468.0 million , respectively. The impact to individual financial statement captions within the condensed consolidating statement of cash flows is footnoted below. Set forth below are Columbia Property Trust's condensed consolidating balance sheets as of December 31, 2017 and 2016 (in thousands), as well as its condensed consolidating statements of operations and its condensed consolidating statements of comprehensive income for 2017 , 2016 , and 2015 (in thousands); and its condensed consolidating statements of cash flows for 2017 , 2016 , and 2015 (in thousands). Condensed Consolidating Balance Sheets (in thousands) As of December 31, 2017 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Assets: Real Estate Assets, at Cost: Land $ — $ — $ 825,208 $ — $ 825,208 Buildings and improvements, net — 2,110 2,061,309 — 2,063,419 Intangible lease assets, net — — 199,260 — 199,260 Construction in progress — — 44,742 — 44,742 Total real estate assets — 2,110 3,130,519 — 3,132,629 Investment in unconsolidated joint ventures — 943,241 1 — 943,242 Cash and cash equivalents 692 5,079 3,796 — 9,567 Investment in subsidiaries 2,238,577 1,186,594 — (3,425,171 ) — Tenant receivables, net of allowance — 30 2,098 — 2,128 Straight-line rent receivable — — 92,235 — 92,235 Prepaid expenses and other assets 317,364 336,598 19,375 (645,654 ) 27,683 Intangible lease origination costs, net — — 42,959 — 42,959 Deferred lease costs, net — — 141,096 — 141,096 Investment in development authority bonds — — 120,000 — 120,000 Total assets $ 2,556,633 $ 2,473,652 $ 3,552,079 $ (4,070,825 ) $ 4,511,539 Liabilities: Line of credit and notes payable, net $ — $ 899,168 $ 715,327 $ (643,310 ) $ 971,185 Bonds payable, net — 693,756 — — 693,756 Accounts payable, accrued expenses, and accrued capital expenditures 732 10,325 113,949 (4 ) 125,002 Dividends payable 23,961 — — — 23,961 Due to affiliates — — 2,340 (2,340 ) — Deferred income 4 81 18,396 — 18,481 Intangible lease liabilities, net — — 27,218 — 27,218 Obligations under capital leases — — 120,000 — 120,000 Total liabilities 24,697 1,603,330 997,230 (645,654 ) 1,979,603 Equity: Total equity 2,531,936 870,322 2,554,849 (3,425,171 ) 2,531,936 Total liabilities and equity $ 2,556,633 $ 2,473,652 $ 3,552,079 $ (4,070,825 ) $ 4,511,539 Condensed Consolidating Balance Sheets (in thousands) As of December 31, 2016 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Assets: Real Estate Assets, at Cost: Land $ — $ — $ 751,351 $ — $ 751,351 Building and improvements, net — 219 2,120,931 — 2,121,150 Intangible lease assets, net — — 193,311 — 193,311 Construction in progress — — 36,188 — 36,188 Real estate assets held for sale, net — 34,956 377,550 — 412,506 Total real estate assets — 35,175 3,479,331 — 3,514,506 Investment in unconsolidated joint ventures — 127,346 — — 127,346 Cash and cash equivalents 174,420 16,509 25,156 — 216,085 Investment in subsidiaries 2,047,922 1,782,752 — (3,830,674 ) — Tenant receivables, net of allowance — — 7,163 — 7,163 Straight-line rent receivable — — 64,811 — 64,811 Prepaid expenses and other assets 317,153 262,216 15,593 (570,687 ) 24,275 Intangible lease origination costs, net — — 54,279 — 54,279 Deferred lease costs, net — — 125,799 — 125,799 Investment in development authority bonds — — 120,000 — 120,000 Other assets held for sale, net — 3,767 41,814 (52 ) 45,529 Total assets $ 2,539,495 $ 2,227,765 $ 3,933,946 $ (4,401,413 ) $ 4,299,793 Liabilities: Lines of credit and notes payable, net $ — $ 447,643 $ 704,585 $ (430,762 ) $ 721,466 Bonds payable, net — 692,972 — — 692,972 Accounts payable, accrued expenses, and accrued capital expenditures — 10,395 120,633 — 131,028 Dividends payable 36,727 — — — 36,727 Due to affiliates — 58 1,534 (1,592 ) — Deferred income — — 19,694 — 19,694 Intangible lease liabilities, net — — 33,375 — 33,375 Obligations under capital leases — — 120,000 — 120,000 Liabilities held for sale, net — 2,651 177,497 (138,385 ) 41,763 Total liabilities 36,727 1,153,719 1,177,318 (570,739 ) 1,797,025 Equity: Total equity 2,502,768 1,074,046 2,756,628 (3,830,674 ) 2,502,768 Total liabilities and equity $ 2,539,495 $ 2,227,765 $ 3,933,946 $ (4,401,413 ) $ 4,299,793 Consolidating Statements of Operations (in thousands) For the Year Ended December 31, 2017 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Revenues: Rental income $ — $ 51 $ 257,368 $ (360 ) $ 257,059 Tenant reimbursements — (60 ) 23,571 — 23,511 Hotel income — — 1,339 — 1,339 Asset and property management fee income 1,908 — 1,874 — 3,782 Other property income — — 3,327 (18 ) 3,309 1,908 (9 ) 287,479 (378 ) 289,000 Expenses: Property operating costs — 308 87,857 (360 ) 87,805 Hotel operating costs — — 2,089 — 2,089 Asset and Property Management Fee Expenses: Related-party — 3 — (3 ) — Other — — 918 — 918 Depreciation — 869 79,525 — 80,394 Amortization — 5 32,398 — 32,403 General and administrative – corporate 259 9,048 25,674 (15 ) 34,966 General and administrative – joint ventures — — 1,454 — 1,454 259 10,233 229,915 (378 ) 240,029 1,649 (10,242 ) 57,564 — 48,971 Other Income (Expense): Interest expense — (44,259 ) (38,238 ) 21,981 (60,516 ) Interest and other income 16,535 7,762 7,213 (21,981 ) 9,529 Loss on early extinguishment of debt — — (325 ) — (325 ) 16,535 (36,497 ) (31,350 ) — (51,312 ) Income (loss) before income taxes, unconsolidated entities, and gains on sales of real estate assets 18,184 (46,739 ) 26,214 — (2,341 ) Income tax expense — (1 ) 214 — 213 Income (loss) from unconsolidated entities 157,857 198,620 — (353,826 ) 2,651 Income before gains on sales of real estate assets 176,041 151,880 26,428 (353,826 ) 523 Gains on sales of real estate assets — 11,050 164,468 — 175,518 Net income $ 176,041 $ 162,930 $ 190,896 $ (353,826 ) $ 176,041 Consolidating Statements of Operations (in thousands) For the Year Ended December 31, 2016 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Revenues: Rental income $ — $ 3,622 $ 362,947 $ (383 ) $ 366,186 Tenant reimbursements — 1,963 67,807 — 69,770 Hotel income — — 22,661 — 22,661 Asset and property management fee income 574 — 1,548 — 2,122 Other property income 406 — 12,804 (406 ) 12,804 980 5,585 467,767 (789 ) 473,543 Expenses: Property operating costs — 3,209 152,142 (383 ) 154,968 Hotel operating costs — — 18,686 — 18,686 Asset and Property Management Fee Expenses: Related-party — 154 — (154 ) — Other — — 1,415 — 1,415 Depreciation — 2,760 105,783 — 108,543 Amortization — 364 56,411 — 56,775 General and administrative – corporate 154 8,566 25,408 (252 ) 33,876 154 15,053 359,845 (789 ) 374,263 826 (9,468 ) 107,922 — 99,280 Other Income (Expense): Interest expense — (46,797 ) (50,302 ) 29,490 (67,609 ) Interest and other income 14,268 15,272 7,238 (29,490 ) 7,288 Loss on early extinguishment of debt — (18,987 ) (10 ) — (18,997 ) 14,268 (50,512 ) (43,074 ) — (79,318 ) Income (loss) before income taxes, unconsolidated entities, and gains on sales of real estate assets 15,094 (59,980 ) 64,848 — 19,962 Income tax expense — (20 ) (425 ) — (445 ) Income (loss) from unconsolidated entities 69,187 113,105 — (189,853 ) (7,561 ) Income before gains (loss) on sales of real estate assets 84,281 53,105 64,423 (189,853 ) 11,956 Gains (loss) on sales of real estate assets — — 72,325 — 72,325 Net income $ 84,281 $ 53,105 $ 136,748 $ (189,853 ) $ 84,281 Consolidating Statements of Operations (in thousands) For the Year Ended December 31, 2015 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Revenues: Rental income $ — $ 2,662 $ 433,763 $ (377 ) $ 436,048 Tenant reimbursements — 1,316 98,339 — 99,655 Hotel income — — 24,309 — 24,309 Asset and property management fee income 171 — 434 — 605 Other property income — — 5,781 (333 ) 5,448 171 3,978 562,626 (710 ) 566,065 Expenses: Property operating costs — 3,065 185,390 (377 ) 188,078 Hotel operating costs — — 19,615 — 19,615 Asset and Property Management Fee Expenses: Related-party — 100 — (100 ) — Other — — 1,816 — 1,816 Depreciation — 2,571 128,919 — 131,490 Amortization — 237 86,891 — 87,128 General and administrative – corporate 152 8,754 21,010 (233 ) 29,683 Acquisition expenses — 11 3,664 — 3,675 152 14,738 447,305 (710 ) 461,485 19 (10,760 ) 115,321 — 104,580 Other Income (Expense): Interest expense — (44,919 ) (67,076 ) 26,699 (85,296 ) Interest and other income 14,141 12,565 7,247 (26,699 ) 7,254 Loss on interest rate swaps — (1,101 ) (9 ) — (1,110 ) Loss on early extinguishment of debt — (1,050 ) (2,099 ) — (3,149 ) 14,141 (34,505 ) (61,937 ) — (82,301 ) Income before income taxes, unconsolidated entities, and gains on sales of real estate assets 14,160 (45,265 ) 53,384 — 22,279 Income tax expense — (25 ) (353 ) — (378 ) Income (loss) from unconsolidated entities 30,459 59,165 — (90,766 ) (1,142 ) Income before gains on sales of real estate assets 44,619 13,875 53,031 (90,766 ) 20,759 Gains on sales of real estate assets — (19 ) 23,879 — 23,860 Net income $ 44,619 $ 13,856 $ 76,910 $ (90,766 ) $ 44,619 Consolidating Statements of Comprehensive Income (in thousands) For the Year Ended December 31, 2017 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Net income $ 176,041 $ 162,930 $ 190,896 $ (353,826 ) $ 176,041 Market value adjustment to interest rate swap 1,786 1,786 — (1,786 ) 1,786 Comprehensive income $ 177,827 $ 164,716 $ 190,896 $ (355,612 ) $ 177,827 For the Year Ended December 31, 2016 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Net income $ 84,281 $ 53,105 $ 136,748 $ (189,853 ) $ 84,281 Market value adjustment to interest rate swap 1,553 1,553 — (1,553 ) 1,553 Comprehensive income $ 85,834 $ 54,658 $ 136,748 $ (191,406 ) $ 85,834 For the Year Ended December 31, 2015 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Net income $ 44,619 $ 13,856 $ 76,910 $ (90,766 ) $ 44,619 Market value adjustment to interest rate swap (1,570 ) (1,570 ) — 1,570 (1,570 ) Settlement of interest rate swap 1,102 1,102 — (1,102 ) 1,102 Comprehensive income $ 44,151 $ 13,388 $ 76,910 $ (90,298 ) $ 44,151 Consolidating Statements of Cash Flows (in thousands) For the Year Ended December 31, 2017 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Cash flows from operating activities $ 3,966 $ (46,268 ) $ 104,226 $ — $ 61,924 Cash Flows From Investing Activities: Net proceeds from the sale of real estate — 49,531 688,100 — 737,631 Investment in real estate and related assets — (2,203 ) (716,093 ) — (718,296 ) Investment in unconsolidated joint ventures — (369,043 ) — — (369,043 ) Distributions in excess of earnings from unconsolidated joint ventures — 1,985 — — 1,985 Investments in subsidiaries (8,671 ) (97,505 ) — 106,176 — Net cash provided by (used in) investing activities (8,671 ) (417,235 ) (27,993 ) 106,176 (347,723 ) Cash Flows From Financing Activities: Borrowings, net of fees — 781,731 — — 781,731 Repayments — (331,000 ) (202,427 ) — (533,427 ) Redemptions of common stock (59,462 ) — — — (59,462 ) Distributions (109,561 ) 1,342 104,834 (106,176 ) (109,561 ) Net cash provided by (used in) financing activities (169,023 ) 452,073 (97,593 ) (106,176 ) 79,281 Net decrease in cash and cash equivalents (173,728 ) (11,430 ) (21,360 ) — (206,518 ) Cash and cash equivalents, beginning of period 174,420 16,509 25,156 — 216,085 Cash and cash equivalents, end of period $ 692 $ 5,079 $ 3,796 $ — $ 9,567 Consolidating Statements of Cash Flows (in thousands) For the Year Ended December 31, 2016 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Cash flows from operating activities $ 53,980 $ 86,846 $ 242,118 $ (189,853 ) $ 193,091 Cash Flows From Investing Activities: Net proceeds from the sale of real estate (1) — — 613,732 — 613,732 Investment in real estate and related assets — (2,157 ) (69,750 ) — (71,907 ) Investment in unconsolidated joint ventures — (16,212 ) — — (16,212 ) Distributions from subsidiaries (2) 321,911 568,480 — (890,391 ) — Net cash provided by investing activities 321,911 550,111 543,982 (890,391 ) 525,613 Cash Flows From Financing Activities: Borrowings, net of fees (3) — 780,577 — — 780,577 Repayments (4) — (1,051,000 ) (44,460 ) — (1,095,460 ) Prepayments to settle debt and interest rate swap (5) — (17,921 ) — — (17,921 ) Redemptions of common stock (53,986 ) — — — (53,986 ) Distributions (6) (148,474 ) (347,073 ) (733,171 ) 1,080,244 (148,474 ) Net cash used in financing activities (202,460 ) (635,417 ) (777,631 ) 1,080,244 (535,264 ) Net increase in cash and cash equivalents 173,431 1,540 8,469 — 183,440 Cash and cash equivalents, beginning of period 989 14,969 16,687 — 32,645 Cash and cash equivalents, end of period $ 174,420 $ 16,509 $ 25,156 $ — $ 216,085 (1) Net proceeds from the sale of real estate increased (decreased) by $(603.7) million and $603.7 million for the parent and non-guarantors, respectively. (2) Distributions from subsidiaries increased (decreased) by $321.9 million , $568.5 million , and $(890.4) million for the parent, issuer, and eliminations, respectively. (3) Borrowings, net of fees, increased (decreased) by $(781.4) million and $781.4 million for the parent and issuer, respectively. (4) Repayments increased (decreased) by $1,090.0 million , $(1,051.0) million , and $(39.0) million for the parent, issuer, and non-guarantors respectively. (5) Prepayments to settle debt and interest rate swap increased (decreased) by $17.9 million and $(17.9) million for the parent and issuer, respectively. (6) Distributions (increased) decreased by $(347.1) million , $(733.2) million , and $1,080.3 million , for the issuer, non-guarantors, and eliminations, respectively. The intercompany transfers, net line item is no longer presented based on the changes to the other line items described herein. For the Year Ended December 31, 2015 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Cash flows from operating activities $ 15,743 $ (50,601 ) $ 273,655 $ (15,717 ) $ 223,080 Cash Flows From Investing Activities: Net proceeds from the sale of real estate (1) — — 596,734 — 596,734 Investments in real estate and related assets (2) — — (1,167,933 ) — (1,167,933 ) Investment in unconsolidated joint ventures — (5,500 ) — — (5,500 ) Investments in subsidiaries (3) (4,615 ) (628,393 ) — 633,008 — Net cash used in investing activities (4,615 ) (633,893 ) (571,199 ) 633,008 (576,699 ) Cash Flows From Financing Activities: Borrowings, net of fees (3) — 2,223,778 — — 2,223,778 Repayments — (1,518,000 ) (336,512 ) — (1,854,512 ) Prepayments to settle debt and interest rate swap — (1,102 ) (2,063 ) — (3,165 ) Redemptions of common stock (17,057 ) — — — (17,057 ) Distributions (4) (112,570 ) (15,717 ) 633,008 (617,291 ) (112,570 ) Net cash provided by (used in) financing activities (129,627 ) 688,959 294,433 (617,291 ) 236,474 Net increase (decrease) in cash and cash equivalents (118,499 ) 4,465 (3,111 ) — (117,145 ) Cash and cash equivalents, beginning of period 119,488 10,504 19,798 — 149,790 Cash and cash equivalents, end of period $ 989 $ 14,969 $ 16,687 $ — $ 32,645 (1) Net proceeds from the sales of real estate increased (decreased) by $(72.4) million , $(524.4) million , and $596.7 million for the parent, issuer, and non-guarantors, respectively. (2) Investments in real estate and related assets increased (decrease) by $57.2 million , $1,007.5 million , and $(1,064.7) million for the parent, issuer, and non-guarantors, respectively. (3) Investments in subsidiaries increased (decreased) by $1,061.1 million , $(628.4) million , and $(432.7) million for the parent, issuer, and eliminations, respectively. (4) Distributions (increased) decreased by $(15.7) million , $633.0 million , and $(617.3) million , for the issuer, non-guarantors, and eliminations, respectively. The intercompany transfers, net line item is no longer presented based on the changes to the other line items described herein.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Columbia Property Trust has evaluated subsequent events in connection with the preparation of its consolidated financial statements and notes thereto included in this report on Form 10-K and noted the following items in addition to those disclosed elsewhere in this report: • On February 7, 2018, the board of directors declared dividends for the first quarter of 2018 in the amount of $0.20 per share, payable on March 15, 2018, to stockholders of record on March 1, 2018. • On February 1, 2018, Columbia Property Trust sold an additional 22.5% interest in University Circle and 333 Market Street to its joint venture partner, Allianz, as described in Note 3, Real Estate Transactions. • On January 5, 2018, Columbia Property Trust paid an aggregate amount of $24.0 million in dividends for the fourth quarter of 2017 to shareholders of record on December 1, 2017.

Schedule III - Real Estate Asse

Schedule III - Real Estate Assets and Accumulated Depreciation and Amortization	12 Months Ended
	Dec. 31, 2017
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]
Schedule III - Real Estate Assets and Accumulated Depreciation and Amortization	Columbia Property Trust, Inc. Initial Costs Costs Capitalized Subsequent to Acquisition Gross Amount at Which Carried at Accumulated Depreciation and Amortization Date of Construction Life on Which Depreciation and Amortization is Computed (b) Description Location Owner- ship % Encum-brances Land Buildings and Improvements Total Land Buildings and Improvements Total (a) Date Acquired ONE & THREE GLENLAKE Atlanta, GA 100 % $ 23,716 (c) $ 13,363 $ 155,465 $ 168,828 $ 2,429 $ 13,989 $ 157,268 $ 171,257 $ 49,203 2003/2008 6/25/2004/ 7/31/2008 0 to 40 years 80 M STREET Washington, D.C. 100 % None 26,248 76,269 102,517 7,080 26,806 82,791 109,597 23,439 2001 6/29/2004 0 to 40 years 263 SHUMAN BOULEVARD Naperville, IL 100 % $ 49,000 7,142 41,535 48,677 (3,344 ) 7,233 38,100 45,333 15,146 1986 7/20/2006 0 to 40 years 95 COLUMBUS Jersey City, NJ 100 % None 29,061 141,544 170,605 13,056 29,712 153,949 183,661 60,366 1989 10/31/2006 0 to 40 years PASADENA CORPORATE PARK Pasadena, CA 100 % None 53,099 59,630 112,729 (893 ) 53,099 58,737 111,836 17,944 1965/2000/ 2002/2003 7/11/2007 0 to 40 years 222 EAST 41ST STREET New York City, NY 100 % None (d) — 324,520 324,520 (25,359 ) — 299,161 299,161 67,336 2001 8/17/2007 0 to 45 years LINDBERGH CENTER Atlanta, GA 100 % None (d) — 262,468 262,468 3,252 — 265,720 265,720 77,417 2002 7/1/2008 0 to 40 years CRANBERRY WOODS DRIVE Cranberry Township, PA 100 % None 15,512 173,062 188,574 6,579 15,512 179,641 195,153 46,136 2009/2010 6/1/2010 0 to 40 years 221 MAIN STREET San Francisco, CA 100 % None 60,509 174,629 235,138 12,927 60,509 187,556 248,065 27,105 1974 4/22/2014 0 to 40 years 650 CALIFORNIA STREET San Francisco, CA 100 % None 75,384 240,441 315,825 13,978 75,384 254,419 329,803 28,925 1964 9/9/2014 0 to 40 years 315 PARK AVENUE SOUTH New York, NY 100 % None 119,633 249,510 369,143 13,130 119,633 262,640 382,273 19,204 1910 1/7/2015 0 to 40 years 116 HUNTINGTON AVENUE Boston, MA 100 % None (e) — 116,290 116,290 47,662 — 163,952 163,952 16,640 1991 1/8/2015 0 to 40 years 229 WEST 43RD STREET New York, NY 100 % None 207,233 292,991 500,224 (553 ) 207,233 292,438 499,671 30,119 1912/1924/ 1932/1947 8/4/2015 0 to 40 years 245-249 WEST 17TH STREET New York, NY 100 % None 113,149 221,517 334,666 — 113,150 221,516 334,666 2,210 1902/1909 10/11/2017 0 to 40 years 218 WEST 18TH STREET New York, NY 100 % None 43,836 139,077 182,913 — 43,836 139,077 182,913 1,437 1912 10/11/2017 0 to 40 years 149 MADISON AVENUE New York, NY 100 % None 59,112 28,989 88,101 1,132 59,112 30,121 89,233 — 1916 11/28/2017 0 to 40 years TOTAL CONSOLIDATED REAL ESTATE ASSETS (f) $ 823,281 $ 2,697,937 $ 3,521,218 $ 91,076 $ 825,208 $ 2,787,086 $ 3,612,294 $ 482,627 UNCONSOLIDATED REAL ESTATE ASSETS (presented at 100% of the Joint Venture's Basis) (g) : MARKET SQUARE Washington, D.C. 51.0 % $ 325,000 $ 152,629 $ 450,757 $ 603,386 $ (41,591 ) $ 152,629 $ 409,166 $ 561,795 $ 29,483 1990 10/28/2015 0 to 40 years UNIVERSITY CIRCLE East Palo Alto, CA 77.5 % None 27,493 278,288 305,781 (99,466 ) 27,757 178,558 206,315 2,839 2001/2002/ 2003 7/6/2017 0 to 40 years 333 MARKET STREET San Francisco, CA 77.5 % None 114,483 292,840 407,323 (41,229 ) 114,484 251,610 366,094 4,038 1979 7/6/2017 0 to 40 years 114 FIFTH AVE New York, NY 49.5 % None — 383,694 383,694 1,824 — 385,518 385,518 27,165 1910 7/6/2017 0 to 40 years 1800 M STREET Washington, D.C. 55.0 % None 125,735 272,353 398,088 31,485 125,735 303,838 429,573 3,863 1975 10/11/2017 0 to 40 years TOTAL UNCONSOLIDATED REAL ESTATE ASSETS 420,340 $ 1,677,932 $ 2,098,272 $ (148,977 ) $ 420,605 $ 1,528,690 $ 1,949,295 $ 67,388 (a) The aggregate cost of consolidated land and buildings and improvements for federal income tax purposes is approximately $3.933 billion . (b) Columbia Property Trust assets are depreciated or amortized using the straight-line method over the useful lives of the assets by class. Generally, tenant improvements are amortized over the shorter of economic life or lease term, lease intangibles are amortized over the respective lease term, building improvements are depreciated over 5 - 25 years, and buildings are depreciated over 40 - 45 years. (c) The One Glenlake Building is subject to a $23.7 million mortgage note. As a result of the acquisition of the Three Glenlake Building, Columbia Property Trust acquired investments in bonds and certain obligations under capital leases in the amount of $120.0 million . (d) Property is owned subject to a long-term ground lease. (e) 116 Huntington Avenue is owned subject to a long-term, pre-paid ground lease. (f) Consolidated real estate assets excludes $3.2 million of corporate assets. (g) The aggregate cost of 100% of the land and buildings and improvements, net of debt, held by unconsolidated joint ventures for federal income tax purposes is approximately $2.025 billion . Columbia Property Trust, Inc. Schedule III – Real Estate Assets and Accumulated Depreciation and Amortization (in thousands) For the Years Ended December 31, 2017 2016 2015 Real Estate: Balance at beginning of year $ 4,243,531 $ 4,948,605 $ 5,050,482 Additions to/improvements of real estate 698,567 41,848 1,162,068 Sale/transfer of real estate (1,285,915 ) (1) (673,164 ) (1,188,083 ) (2) Write-offs of building and tenant improvements (3,087 ) (5,559 ) (1,552 ) Write-offs of intangible assets (3) (14,432 ) (30,435 ) (12,614 ) Write-offs of fully depreciated assets (26,370 ) (37,764 ) (61,696 ) Balance at end of year $ 3,612,294 $ 4,243,531 $ 4,948,605 Accumulated Depreciation and Amortization: Balance at beginning of year $ 729,025 $ 863,724 $ 973,920 Depreciation and amortization expense 97,732 140,823 183,492 Sale/transfer of real estate (302,157 ) (1) (203,248 ) (221,481 ) (2) Write-offs of tenant improvements (1,406 ) (4,336 ) (948 ) Write-offs of intangible assets (3) (14,197 ) (30,174 ) (9,563 ) Write-offs of fully depreciated assets (26,370 ) (37,764 ) (61,696 ) Balance at end of year $ 482,627 $ 729,025 $ 863,724 (1) Includes the transfer of 100% of University Circle and 333 Market Street to unconsolidated joint ventures, in which Columbia Property Trust currently owns a 77.5% interest. (2) Includes the transfer of 100% of the Market Square Buildings to an unconsolidated joint venture, in which Columbia Property Trust currently owns a 51% interest. (3) Consists of write-offs of intangible lease assets related to lease restructurings, amendments, and terminations.

Summary of Significant Accoun26

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements of Columbia Property Trust have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") and include the accounts of Columbia Property Trust, Columbia Property Trust OP, and any variable interest entity ("VIE") in which Columbia Property Trust or Columbia Property Trust OP was deemed the primary beneficiary. With respect to entities that are not VIEs, Columbia Property Trust's consolidated financial statements shall also include the accounts of any entity in which Columbia Property Trust, Columbia Property Trust OP, or its subsidiaries own a controlling financial interest and any limited partnership in which Columbia Property Trust, Columbia Property Trust OP, or its subsidiaries own a controlling general partnership interest. In determining whether Columbia Property Trust or Columbia Property Trust OP has a controlling interest, the following factors are considered, among other things: the ownership of voting interests, protective rights, and participatory rights of the investors. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying consolidated financial statements and the accompanying notes. Actual results could differ from those estimates.
Fair Value Measurements	Fair Value Measurements Columbia Property Trust estimates the fair value of its assets and liabilities (where currently required under GAAP) consistent with the provisions of Accounting Standard Codification 820, Fair Value Measurements ("ASC 820"). Under this standard, fair value is defined as the price that would be received upon sale of an asset or paid upon transfer of a liability in an orderly transaction between market participants at the measurement date. While various techniques and assumptions can be used to estimate fair value depending on the nature of the asset or liability, the accounting standard for fair value measurements and disclosures provides the following fair value technique parameters and hierarchy, depending upon availability: Level 1 – Assets or liabilities for which the identical term is traded on an active exchange, such as publicly traded instruments or futures contracts. Level 2 – Assets and liabilities valued based on observable market data for similar instruments. Level 3 – Assets or liabilities for which significant valuation assumptions are not readily observable in the market. Such assets or liabilities are valued based on the best available data, some of which may be internally developed. Significant assumptions may include risk premiums that a market participant would consider.
Real Estate Assets	Real Estate Assets Real estate assets are stated at cost, less accumulated depreciation and amortization. Amounts capitalized to real estate assets consist of the cost of acquisition or construction, and any tenant improvements or major improvements and betterments that extend the useful life of the related asset. All repairs and maintenance are expensed as incurred. Additionally, Columbia Property Trust capitalizes interest while the development of a real estate asset is in progress. During the years ended December 31, 2017 and 2016 , $0.7 million and $0.3 million of interest was capitalized, respectively. Columbia Property Trust is required to make subjective assessments as to the useful lives of its depreciable assets. To determine the appropriate useful life of an asset, Columbia Property Trust considers the period of future benefit of the asset. These assessments have a direct impact on net income. The estimated useful lives of its assets by class are as follows: Buildings 40-45 years Building and site improvements 5-25 years Tenant improvements Shorter of economic life or lease term Intangible lease assets Lease term
Evaluating the Recoverability of Real Estate Assets	Evaluating the Recoverability of Real Estate Assets Columbia Property Trust continually monitors events and changes in circumstances that could indicate that the carrying amounts of its real estate and related intangible assets, of both operating properties and properties under construction, may not be recoverable. When indicators of potential impairment are present that suggest that the carrying amounts of real estate assets and related intangible assets (liabilities) may not be recoverable, Columbia Property Trust assesses the recoverability of these assets by determining whether the respective carrying values will be recovered through the estimated undiscounted future operating cash flows expected from the use of the assets and their eventual disposition. In the event that such expected undiscounted future cash flows do not exceed the carrying values, Columbia Property Trust adjusts the carrying value of the real estate assets and related intangible assets to the estimated fair values, pursuant to the property, plant, and equipment accounting standard for the impairment or disposal of long-lived assets, and recognizes an impairment loss. Estimated fair values are calculated based on the following hierarchy of information: (Level 1) recently quoted market prices, (Level 2) market prices for comparable properties, or (Level 3) the present value of future cash flows, including estimated residual value. Certain of Columbia Property Trust's assets may be carried at an amount that exceeds that which could be realized in a current disposition transaction. Columbia Property Trust has determined that the carrying values of its real estate assets and related intangible assets are recoverable as of December 31, 2017 . Projections of expected future operating cash flows require that Columbia Property Trust estimates future market rental income amounts subsequent to the expiration of current lease agreements, property operating expenses, the number of months it takes to re-lease the property, and the number of years the property is held for investment, among other factors. Due to the inherent subjectivity of the assumptions used to project future cash flows, estimated fair values may differ from the values that would be realized in market transactions.
Assets Held for Sale	Assets Held for Sale Columbia Property Trust classifies properties as held for sale according to Accounting Standard Codification 360, Accounting for the Impairment or Disposal of Long-Lived Assets ("ASC 360"). According to ASC 360, properties, having separately identifiable operations and cash flows, are considered held for sale when the following criteria are met: • Management, having the authority to approve the action, commits to a plan to sell the property. • The property is available for immediate sale in its present condition subject only to terms that are usual and customary for sales of such property. • An active program to locate a buyer and other actions required to complete the plan to sell the property have been initiated. • The property is being actively marketed for sale at a price that is reasonable in relation to its current fair value. • Actions required to complete the plan indicate that it is unlikely that significant changes to the plan will be made or that the plan will be withdrawn. • The sale of the property is probable (i.e. typically subject to a binding sale contract with a non-refundable deposit), and transfer of the property is expected to qualify for recognition as a completed sale, within one year. At such time that a property is determined to be held for sale, its carrying amount is adjusted to the lower of its depreciated book value or its estimated fair value, less costs to sell, and depreciation is no longer recognized; and assets and liabilities are required to be classified as held for sale on the accompanying consolidated balance sheet.
Allocation of Purchase Price of Acquired Assets	Allocation of Purchase Price of Acquired Assets Upon the acquisition of real properties, Columbia Property Trust allocates the purchase price of properties to tangible assets, consisting of land, building, site improvements, and identified intangible assets and liabilities, including the value of in-place leases, based in each case on Columbia Property Trust's estimate of their fair values in accordance with ASC 820 (see Fair Value Measurements section above for additional details). Columbia Property Trust adopted ASU 2017-01, as described in the Recent Accounting Pronouncements section below, effective October 1, 2017. As a result, transaction costs for properties acquired in the fourth quarter have been capitalized and included in the purchase price allocated for properties acquired in the period. Prior to October 1, 2017, transaction costs were expensed and included in acquisition expense on the accompanying statements of operations. The fair values of the tangible assets of an acquired property (which includes land, building, and site improvements) are determined by valuing the property as if it were vacant, and the "as-if-vacant" value is then allocated to land, building, and site improvements based on management's determination of the relative fair value of these assets. Management determines the as-if-vacant fair value of a property using methods similar to those used by independent appraisers. Factors considered by management in performing these analyses include an estimate of carrying costs during the expected lease-up periods considering current market conditions and costs to execute similar leases, including leasing commissions and other related costs. In estimating carrying costs, management includes real estate taxes, insurance, and other operating expenses during the expected lease-up periods based on current market demand.
Intangible Assets and Liabilities Arising From In-Place Leases Where Columbia Property Trust is the Lessor	Intangible Assets and Liabilities Arising From In-Place Leases Where Columbia Property Trust Is the Lessor As further described below, in-place leases with Columbia Property Trust as the lessor may have values related to: direct costs associated with obtaining a new tenant, opportunity costs associated with lost rentals that are avoided by acquiring an in-place lease, tenant relationships, and effective contractual rental rates that are above or below market rates: • Direct costs associated with obtaining a new tenant, including commissions, tenant improvements, and other direct costs, are estimated based on management's consideration of current market costs to execute a similar lease. Such direct costs are included in intangible lease origination costs in the accompanying consolidated balance sheets and are amortized to expense over the remaining terms of the respective leases. • The value of opportunity costs associated with lost rentals avoided by acquiring an in-place lease is calculated based on contractual amounts to be paid pursuant to the in-place leases over a market absorption period for a similar lease. Such opportunity costs ("Absorption Period Costs") are included in intangible lease assets in the accompanying consolidated balance sheets and are amortized to expense over the remaining terms of the respective leases. • The value of effective rental rates of in-place leases that are above or below the market rates of comparable leases is calculated based on the present value (using a discount rate that reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be received pursuant to the in-place leases and (ii) management's estimate of fair market lease rates for the corresponding in-place leases. This calculation includes significantly below- market renewal options for which exercise of the renewal option appears to be reasonably assured. These intangible assets or liabilities are measured over the actual or assumed (in the case of renewal options) remaining lease terms. The capitalized above-market and below-market lease values are recorded as intangible lease assets or liabilities and amortized as an adjustment to rental income over the remaining terms of the respective leases.
Intangible Assets and Liabilities Arising From In-Place Leases Where Columbia Property Trust is the Lessee	Intangible Assets and Liabilities Arising From In-Place Leases Where Columbia Property Trust Is the Lessee In-place ground leases where Columbia Property Trust is the lessee may have positive or negative value associated with effective contractual rental rates that are above or below market rates at the time of execution or assumption. Such values are calculated based on the present value (using a discount rate that reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to the in-place lease and (ii) management's estimate of fair market lease rates for the corresponding in-place lease at the time of execution or assumption. This calculation includes significantly below-market renewal options for which exercise of the renewal option appears to be reasonably assured. These intangible assets and liabilities are measured over the actual or assumed (in the case of renewal options) remaining lease terms. The capitalized above-market and below-market in-place lease values are recorded as intangible lease liabilities and assets, respectively, and are amortized as an adjustment to property operating cost over the remaining term of the respective leases.
Cash and Cash Equivalents	Cash and Cash Equivalents Columbia Property Trust considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. Cash equivalents may include cash and short-term investments. Short-term investments are stated at cost, which approximates fair value as of December 31, 2017 and 2016 .
Tenant Receivables, Net	Tenant Receivables, Net Tenant receivables consist of rental and reimbursement billings due from tenants. Tenant receivables are recorded at the original amount earned, less an allowance for any doubtful accounts, which approximates fair value. Management assesses the realizability of tenant receivables on an ongoing basis and provides for allowances as such balances, or portions thereof, become uncollectible.
Straight Line Rent Receivable	Straight Line Rent Receivable Straight line rent receivable reflects the amount of cumulative adjustments necessary to present rental income on a straight-line basis. Columbia Property Trust recognizes revenues on a straight-line basis, ratably over the term of each lease; however, leases often provide for payment terms that differ from the revenue recognized. When the amount of cash received is less than the amount of revenue recognized, typically early in the lease, straight line rent receivable is recorded for the difference. The receivable is depleted during periods later in the lease when the amount of cash paid by the tenant is greater than the amount of revenue recognized.
Prepaid Expenses and Other Assets	Prepaid Expenses and Other Assets Prepaid expenses and other assets primarily include earnest money deposits, escrow accounts held by lenders to pay future real estate taxes, insurance and tenant improvements, notes receivable, nontenant receivables, prepaid taxes, insurance and operating costs, unamortized deferred financing costs related to the line of credit (the "Revolving Credit Facility"), interest rate swaps (when in an asset position), certain corporate assets, hotel inventory, and deferred tax assets. Prepaid expenses are recognized over the period to which the good or service relates. Other assets are written off when the asset no longer has future value, or when the company is no longer obligated for the corresponding liability.
Deferred Financing and Deferred Lease Costs	Deferred Financing Costs Deferred financing costs include costs incurred to secure debt from third-party lenders. Deferred financing costs, except for costs related to the Revolving Credit Facility, are presented as a direct reduction to the carrying amount of the related debt for all periods presented. Deferred financing costs related to the Revolving Credit Facility are included in prepaid expenses and other assets. Deferred Lease Costs Deferred lease costs include costs incurred to procure leases that are paid to third parties or tenants, and incentives that are provided to tenants under the terms of their leases. These costs are capitalized and amortized on a straight-line basis over the terms of the lease. Amortization of third-party leasing costs is reflected as amortization expense, and amortization of lease incentives is reflected as an adjustment to rental income.
Investments in Development Authority Bonds and Obligations Under Capital Leases	Investments in Development Authority Bonds and Obligations Under Capital Leases In connection with the acquisition of certain real estate assets, Columbia Property Trust has assumed investments in development authority bonds and corresponding obligations under capital leases of land or buildings. The county development authority issued bonds to developers to finance the initial development of these projects, a portion of which was then leased back to the developer under a capital lease. This structure enabled the developer to receive property tax abatements over the concurrent terms of the development authority bonds and capital leases. The remaining property tax abatement benefits transferred to Columbia Property Trust upon assumption of the bonds and corresponding capital leases at acquisition. The development authority bonds and the obligations under the capital leases are both recorded at their net present values, which Columbia Property Trust believes approximates fair value. The related amounts of interest income and expense are recognized as earned in equal amounts and, accordingly, do not impact net income.
Line of Credit and Notes Payable and Bonds Payable	Line of Credit and Notes Payable Certain mortgage notes included in line of credit and notes payable in the accompanying consolidated balance sheets were assumed upon the acquisition of real properties. When debt is assumed, Columbia Property Trust records the loan at fair value. The fair value adjustment is amortized to interest expense over the term of the loan using the effective interest method. As described in the Deferred Financing Costs section above, line of credit and notes payable is presented on the accompanying consolidated balance sheet net of deferred financing costs related to term loans and notes payable of $3.0 million and $3.1 million as of December 31, 2017 and December 31, 2016 , respectively. Bonds Payable In August 2016, Columbia Property Trust issued $350 million of its 10 -year unsecured 3.650% senior notes at 99.626% of their face value (the "2026 Bonds Payable"). In March 2015, Columbia Property Trust issued $350.0 million of its 10 -year unsecured 4.150% senior notes at 99.859% of their face value (the "2025 Bonds Payable"). The discount on the 2026 Bonds Payable and the 2025 Bonds Payable is amortized to interest expense over the term of the bonds using the effective-interest method.
Preferred Stock, Common Stock and Distributions	Preferred Stock Columbia Property Trust is authorized to issue up to 100.0 million shares of one or more classes or series of preferred stock with a par value of $0.01 per share. Columbia Property Trust's board of directors may determine the relative rights, preferences, and privileges of each class or series of preferred stock issued, which may be more beneficial than the rights, preferences, and privileges attributable to Columbia Property Trust's common stock. To date, Columbia Property Trust has not issued any shares of preferred stock. Common Stock The par value of Columbia Property Trust's issued and outstanding shares of common stock is classified as common stock, with the remainder allocated to additional paid-in capital. Distributions To maintain its status as a REIT, Columbia Property Trust is required by the Internal Revenue Code of 1986, as amended (the "Code"), to make distributions to stockholders each taxable year equal to at least 90% of its REIT taxable income, computed without regard to the dividends-paid deduction and by excluding net capital gains attributable to stockholders ("REIT taxable income"). Distributions to the stockholders are determined by the board of directors of Columbia Property Trust and are dependent upon a number of factors relating to Columbia Property Trust, including funds available for payment of distributions, financial condition, the timing of property acquisitions, capital expenditure requirements, and annual distribution requirements in order to maintain Columbia Property Trust's status as a REIT under the Code.
Interest Rate Swap Agreements	Interest Rate Swap Agreements Columbia Property Trust enters into interest rate swap contracts to mitigate its interest rate risk on the related financial instruments. Columbia Property Trust does not enter into derivative or interest rate transactions for speculative purposes; however, certain of its derivatives may not qualify for hedge accounting treatment. Columbia Property Trust records the fair value of its interest rate swaps on its consolidated balance sheet either as prepaid expenses and other assets or as accounts payable, accrued expenses, and accrued capital expenditures. Changes in the fair value of the effective portion of interest rate swaps that are designated as cash flow hedges are recorded as other comprehensive income, while changes in the fair value of the ineffective portion of a hedge, if any, is recognized currently in earnings. Changes in the fair value of interest rate swaps that do not qualify for hedge accounting treatment are recorded as gain or loss on interest rate swaps. Amounts received or paid under interest rate swap agreements are recorded as interest expense for contracts that qualify for hedge accounting treatment and as loss on interest rate swaps for contracts that do not qualify for hedge accounting treatment.
Revenue Recognition	Revenue Recognition All leases on real estate assets held by Columbia Property Trust are classified as operating leases, and the related base rental income is generally recognized on a straight-line basis over the terms of the respective leases. Tenant reimbursements are recognized as revenue in the period that the related operating cost is incurred and are billed to tenants pursuant to the terms of the underlying leases. Rental income and tenant reimbursements collected in advance are recorded as deferred income in the accompanying consolidated balance sheets. Management fees earned by Columbia Property Trust for services provided to certain of its unconsolidated joint ventures are recorded as asset and property management fee income during the period in which such services are provided. Lease termination fees are recorded as other property income and recognized on a straight-line basis from when Columbia Property Trust receives notification of termination through the date the tenant has lost the right to lease the space and Columbia Property Trust has satisfied all obligations under the related lease or lease termination agreement. In conjunction with certain acquisitions, Columbia Property Trust has entered into master lease agreements with various sellers, whereby the sellers are obligated to pay rent pertaining to certain nonrevenue-producing spaces either at the time of, or subsequent to, the property acquisition. These master leases were established at the time of acquisition to mitigate the potential negative effects of lost rental revenues and expense reimbursement income. Columbia Property Trust records payments received under master lease agreements as a reduction of the basis of the underlying property rather than rental income. There were no proceeds received from master leases during 2017 , 2016 , or 2015 . Prior to disposition on January 31, 2017, Columbia Property Trust owned the Key Center Marriott, a full-service hotel, through a taxable REIT subsidiary. Revenues derived from the operations of the hotel include, but are not limited to, revenues from rental of rooms, food and beverage sales, telephone usage, and other service revenues. Revenue was recognized when rooms were occupied, when services performed, and when products were delivered.
Income Taxes	Income Taxes Columbia Property Trust has elected to be taxed as a REIT under the Code, and has operated as such beginning with its taxable year ended December 31, 2003. To qualify as a REIT, Columbia Property Trust must meet certain organizational and operational requirements, including a requirement to distribute at least 90% of its REIT taxable income, as defined by the Code, to its stockholders. As a REIT, Columbia Property Trust generally is not subject to income tax on income it distributes to stockholders. Columbia Property Trust's stockholder distributions typically exceed its taxable income due to the inclusion of noncash expenses, such as depreciation, in taxable income. As a result, Columbia Property Trust typically does not incur federal income taxes other than as described in the following paragraph. Columbia Property Trust is, however, subject to certain state and local taxes related to the operations of properties in certain locations, which have been provided for in the accompanying consolidated financial statements. Columbia Property Trust TRS, LLC, Columbia KCP TRS, LLC, and Columbia Energy TRS, LLC (collectively, the "TRS Entities") are wholly owned subsidiaries of Columbia Property Trust and are organized as Delaware limited liability companies. The TRS Entities, among other things, provide tenant services that Columbia Property Trust, as a REIT, cannot otherwise provide. Columbia Property Trust has elected to treat the TRS Entities as taxable REIT subsidiaries. Columbia Property Trust may perform certain additional, noncustomary services for tenants of its buildings through the TRS Entities; however, any earnings related to such services are subject to federal and state income taxes. In addition, for Columbia Property Trust to continue to qualify as a REIT, Columbia Property Trust must limit its investments in taxable REIT subsidiaries to 25% of the value of the total assets. The TRS Entities' deferred tax assets and liabilities represent temporary differences between the financial reporting basis and the tax basis of assets and liabilities based on the enacted rates expected to be in effect when the temporary differences reverse. If applicable, Columbia Property Trust records interest and penalties related to uncertain tax positions as general and administrative expense in the accompanying consolidated statements of operations.
Segment Information	Segment Information As of December 31, 2017 , Columbia Property Trust's reportable segments are determined based on the geographic markets in which it has significant investments. Columbia Property Trust considers geographic location when evaluating its portfolio composition, and in assessing the ongoing operations and performance of its properties (see Note 14, Segment Information ).
Reclassification	Reclassification Certain prior period amounts may be reclassified to conform to the current-period financial statement presentation. Within revenues on the accompanying consolidated statements of operations, management fees earned from unconsolidated joint ventures have been reclassified from other property income to a dedicated line item, asset and property management fee income, for all periods presented.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2017, the Financial Accounting Standards Board (the "FASB") issued Accounting Standard Update 2017-12, Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12"). ASU 2017-12 aligns reporting requirements for hedging relationships with risk management activities and simplifies the application of hedge accounting. ASU 2017-12 eliminates the concept of recognizing periodic hedge ineffectiveness for cash flow hedges and allows for ongoing qualitative, rather than quantitative, testing of hedge effectiveness. ASU 2017-12 will be effective for Columbia Property Trust on January 1, 2019, with early adoption permitted. Columbia Property Trust elected to early adopt ASU 2017-12 effective December 1, 2017. The adoption of ASU 2017-12 resulted in a simplified process to determine the ongoing effectiveness of its cash flow hedge with no material impact on its consolidated financial statements or other disclosures. In February 2017, the FASB issued Accounting Standard Update 2017-05 , Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Non-Financial Assets ("ASU 2017-05"), which will apply to the partial sale of non-financial assets, including real estate assets, to unconsolidated joint ventures. ASU 2017-05 will require Columbia Property Trust to measure its residual joint venture interest in the properties transferred to unconsolidated joint ventures at fair value as of the transaction date by recognizing a gain or loss on 100% of the asset transferred (i.e. to fully step-up the basis of the residual investment in the joint venture). Columbia Property Trust will adopt the new rule effective January 1, 2018 on a modified retrospective basis by recording a cumulative-effect adjustment to equity equal to the original gain or loss as of the respective transaction dates, adjusted to reflect the impact of depreciating the additional step-ups through January 1, 2018. The adoption of this standard will result in an increase to investment in unconsolidated joint ventures and equity by $357.8 million for the investments in the Market Square, 333 Market Street, and University Circle properties. In January 2017, the FASB issued Accounting Standards Update 2017-01, Clarifying the Definition of a Business ("ASU 2017-01"), which provides a more narrow definition of a business to be used in determining the accounting treatment of acquisitions. As a result, under the new standard, many acquisitions previously classified as business combinations will be treated as asset acquisitions. For asset acquisitions, unlike business combinations, transaction costs may be capitalized, and purchase price may be allocated on a relative fair-value basis. Columbia Property Trust elected to early adopt ASU 2017-01 as of October 1, 2017. As a result, transaction costs of $2.2 million were capitalized during the fourth quarter related to the acquisitions of 245-249 West 17th Street, 218 West 18th Street, and 149 Madison Avenue. See Note 3, Real Estate Transactions , for more information about these acquisitions. In February 2016, the FASB issued Accounting Standards Update 2016-02 , Leases ("ASU 2016-02"), which amends the existing standards for lease accounting by requiring lessees to recognize most leases on their balance sheets and by making targeted changes to lessor accounting and reporting. The new standard will require lessees to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months, and classify such leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase of the leased asset by the lessee, or not. This classification will determine whether the lease expense is recognized based on an effective interest method (finance leases) or on a straight-line basis over the term of the lease (operating leases). Leases with a term of 12 months or less will be accounted for using an approach that is similar to existing guidance for operating leases today. The new standard requires lessors to account for leases, using an approach that is substantially equivalent to existing guidance as applies to sales-type leases, direct financing leases, and operating leases. ASU 2016-02 will be effective for Columbia Property Trust on January 1, 2019 and supersedes previous leasing standards. Columbia Property Trust is primarily a lessor and is monitoring additional clarification regarding the treatment of certain features of its lease agreements that might be classified as non-lease components. Columbia Property Trust is also a lessee, primarily on ground leases, and it is evaluating the impact of ASU 2016-02 on accounting for such leases. In May 2014, the FASB issued Accounting Standards Update 2014-09, Revenue from Contracts with Customers ("ASU 2014-09"), which establishes a comprehensive model to account for revenues arising from contracts with customers. ASU 2014-09 applies to all contracts with customers, except those that are within the scope of other topics in the FASB's Accounting Standards Codification, such as real estate leases. ASU 2014-09 will require companies to perform a five-step analysis of transactions to determine when and how revenue is recognized. Columbia Property Trust expects the new standard to apply primarily to fees earned from managing properties owned by its unconsolidated joint ventures and certain parking agreements. Revenues for such services represented $6.7 million , $3.6 million , and $1.8 million , or 2.3% , 0.8% , and 0.3% of total revenues, for the years ended December 31, 2017, 2016, and 2015, respectively. Revenues derived from leases, which are excluded from ASU 2014-09 represented $281.0 million , $447.3 million , and $539.9 million , or 97.2% , 94.5% , and 95.4% of total revenues for the years ended December 31, 2017, 2016, and 2015, respectively. Given the structure of the asset and property management agreements currently in place with unconsolidated joint ventures and the parking agreements currently in place with existing tenants, Columbia Property Trust does not expect ASU 2014-09 to materially impact the timing or amount of revenue recognition; however, Columbia Property Trust will be required to provide more extensive disclosures about its revenue streams and contracts with customers. ASU 2014-09 was effective for Columbia Property Trust on January 1, 2018. Columbia Property Trust will use the modified retrospective approach of adoption, which will result in the recognition of a cumulative effect adjustment to equity, with no retrospective adjustments to prior periods.

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Schedule of Estimated Useful Lives for Real Estate Assets	The estimated useful lives of its assets by class are as follows: Buildings 40-45 years Building and site improvements 5-25 years Tenant improvements Shorter of economic life or lease term Intangible lease assets Lease term
Major Classes of Assets and Liabilities Classified as Held For Sale	The major classes of assets and liabilities classified as held for sale as of December 31, 2016 , are provided below (in thousands): December 31, 2016 Real Estate Assets Held for Sale: Real Estate Assets, at Cost: Land $ 30,243 Buildings and improvements, less accumulated depreciation of $152,246 366,126 Intangible lease assets, less accumulated amortization of $28,545 13,365 Construction in progress 2,772 Total real estate assets held for sale, net $ 412,506 Other Assets Held for Sale: Tenant receivables, net of allowance for doubtful accounts $ 1,722 Straight-line rent receivable 20,221 Prepaid expenses and other assets 3,184 Intangible lease origination costs, less accumulated amortization of $22,949 1,815 Deferred lease costs, less accumulated amortization of $11,203 18,587 Total other assets held for sale, net $ 45,529 Liabilities Held for Sale: Accounts payable, accrued expenses, and accrued capital expenditures $ 34,812 Deferred income 4,214 Intangible lease liabilities, less accumulated amortization of $1,239 2,737 Total liabilities held for sale, net $ 41,763
Schedule of Intangible Assets and Liabilities	As of December 31, 2017 and 2016 , Columbia Property Trust had the following gross intangible in-place lease assets and liabilities, excluding amounts held for sale (in thousands): Intangible Lease Assets Intangible Lease Origination Costs Intangible Below-Market In-Place Lease Liabilities Above-Market In-Place Lease Assets Absorption Period Costs December 31, 2017 Gross $ 2,481 $ 149,927 $ 100,424 $ 46,878 Accumulated Amortization (833 ) (70,465 ) (57,465 ) (19,660 ) Net $ 1,648 $ 79,462 $ 42,959 $ 27,218 December 31, 2016 Gross $ 10,589 $ 154,582 $ 128,857 $ 77,939 Accumulated Amortization (9,305 ) (83,254 ) (74,578 ) (44,564 ) Net $ 1,284 $ 71,328 $ 54,279 $ 33,375 During 2017 , 2016 , and 2015 , Columbia Property Trust recognized the following amortization of intangible lease assets and liabilities (in thousands): Intangible Lease Assets Intangible Lease Origination Costs Intangible Below-Market In-Place Lease Liabilities Above-Market In-Place Lease Assets Absorption Period Costs For the Years Ended December 31, 2017 $ 519 $ 16,807 $ 10,124 $ 6,883 2016 $ 2,513 $ 28,718 $ 17,501 $ 12,996 2015 $ 4,412 $ 45,972 $ 28,530 $ 19,345 The remaining net intangible assets and liabilities as of December 31, 2017 , excluding amounts held for sale, will be amortized as follows (in thousands): Intangible Lease Assets Intangible Lease Origination Costs Intangible Below-Market In-Place Lease Liabilities Above-Market In-Place Lease Assets Absorption Period Costs For the Years Ending December 31, 2018 $ 203 $ 16,898 $ 9,566 $ 6,325 2019 203 14,665 8,651 5,968 2020 203 12,800 7,770 4,535 2021 203 8,112 3,727 1,591 2022 203 6,585 2,708 1,287 Thereafter 633 20,402 10,537 7,512 $ 1,648 $ 79,462 $ 42,959 $ 27,218 Weighted-average amortization period 8 years 5 years 5 years 6 years
Schedule of Net Below-Market Lease Asset Amortization	As of December 31, 2017 , the remaining net below-market lease asset will be amortized as follows (in thousands): For the Years Ending December 31: 2018 $ 2,549 2019 2,549 2020 2,549 2021 2,549 2022 2,549 Thereafter 105,405 $ 118,150 Weighted-average amortization period 47 years
Schedule of Interest Rate Derivatives	Years Ended December 31, 2017 2016 2015 Market value adjustment to interest rate swaps designated as hedging instruments and included in other comprehensive income $ 1,786 $ 1,553 $ (1,570 ) Loss on interest rate swap recognized through earnings $ — $ — $ (1,110 ) The following tables provide additional information related to Columbia Property Trust's interest rate swaps as of December 31, 2017 and 2016 (in thousands): Estimated Fair Value as of December 31, Instrument Type Balance Sheet Classification 2017 2016 Derivatives Designated as Hedging Instruments: Interest rate contracts Prepaid expenses and other assets $ 903 $ — Interest rate contracts Accounts payable $ — $ (882 )

Real Estate Transactions (Table

Real Estate Transactions (Tables)	12 Months Ended
	Dec. 31, 2017
Business Acquisitions and Dispositions [Abstract]
Interests in Properties Acquired	During 2017, 2016, and 2015, Columbia Property Trust acquired the following properties and partial interests in properties: Property Location Date Percent Acquired Purchase Price (1) 2017 149 Madison Avenue New York, NY November 28, 2017 100.0 % $ 87,700 1800 M Street Washington, D.C. October 11, 2017 55.0 % $ 231,550 (2) 245-249 West 17th Street & 218 West 18th Street New York, NY October 11, 2017 100.0 % $ 514,100 114 Fifth Avenue New York, NY July 6, 2017 49.5 % $ 108,900 (2) 2015 229 West 43rd Street New York NY August 4, 2015 100.0 % $ 516,000 116 Huntington Avenue Boston, MA January 8, 2015 100.0 % $ 152,000 315 Park Avenue South & 1881 Campus Commons New York, NY & Reston, VA January 7, 2015 100.0 % $ 436,000 (1) Exclusive of transaction costs and price adjustments. See purchase price allocation table below for a breakout of the net purchase price for wholly-owned properties. (2) Purchase price is for our partial interests in the properties. These properties are owned through unconsolidated joint ventures. Purchase Price Allocations for Consolidated Property Acquisitions: 149 Madison Avenue 245-249 West 17th Street 218 West 18th Street 229 West 43rd Street 116 Huntington 315 Park Avenue 1881 Campus Commons Location New York, NY New York, NY New York, NY New York, NY Boston, MA New York, NY Reston, VA Date Acquired November 28, 2017 October 11, 2017 October 11, 2017 August 4, 2015 January 8, 2015 January 7, 2015 January 7, 2015 Purchase Price: Land $ 59,112 $ 113,149 $ 43,836 $ 207,233 — $ 119,633 $ 7,179 Building and improve-ments 28,989 194,109 126,957 265,952 108,383 232,598 49,273 Intangible lease assets — 27,408 12,120 27,039 7,907 16,912 4,643 Intangible below market ground lease assets — — — — 30,244 — — Intangible lease origin- ation costs — 13,062 4,168 10,059 2,669 4,148 1,603 Intangible below market lease liability — (7,131 ) (11,757 ) — (1,878 ) (7,487 ) (97 ) Total purchase price $ 88,101 $ 340,597 $ 175,324 $ 510,283 147,325 $ 365,804 $ 62,601
Business Acquisition, Pro Forma Information	The following unaudited pro forma statements of operations presented for 2017 , 2016 , and 2015 , have been prepared for Columbia Property Trust to give effect to the acquisitions of 245-249 West 17th Street, 218 West 18th Street, and 149 Madison Avenue as if the acquisitions had occurred on January 1, 2016; and 315 Park Avenue South, 1881 Campus Commons, 116 Huntington Avenue, and 229 West 43rd Street as if the acquisitions had occurred on January 1, 2014. The following unaudited pro forma financial results for Columbia Property Trust have been prepared for informational purposes only and are not necessarily indicative of future results or of actual results that would have been achieved had these acquisitions been consummated as of January 1, 2016 and January 1, 2014 (in thousands): 2017 2016 2015 Revenues $ 319,064 $ 511,306 $ 582,699 Net income $ 183,318 $ 93,537 $ 46,363 Net income per share – basic $ 1.51 $ 0.76 $ 0.37 Net income per share – diluted $ 1.51 $ 0.76 $ 0.37
Schedule of Properties Sold	During 2017 , 2016 , and 2015 , Columbia Property Trust sold the following properties and partial interest in properties: Property Location Date % Sold Sales Price (1) (in thousands) Gain (Loss) on Sale (rounded, in thousands) 2017 University Circle & 333 Market Street (2) San Francisco, CA July 6, 2017 22.5 % (3) $ 234,000 (2)(3) $ 102,400 Key Center Tower & Marriott (4) Cleveland, OH January 31, 2017 100.0 % $ 267,500 $ 9,500 Houston Properties (5) Houston, TX January 6, 2017 100.0 % $ 272,000 $ 63,700 2016 SanTan Corporate Center Phoenix, AZ December 15, 2016 100.0 % $ 58,500 $ 9,800 Sterling Commerce Dallas, TX November 30, 2016 100.0 % $ 51,000 $ 12,500 9127 South Jamaica Street Denver, CO October 12, 2016 100.0 % $ 19,500 $ — (6) 80 Park Plaza Newark, NJ September 30, 2016 100.0 % $ 174,500 $ 21,600 9189, 9191 & 9193 South Jamaica Street Denver, CO September 22, 2016 100.0 % $ 122,000 $ 27,200 800 North Frederick Suburban, MD July 8, 2016 100.0 % $ 48,000 $ 2,100 100 East Pratt (7) Baltimore, MD March 31, 2016 100.0 % $ 187,000 $ (300 ) 2015 1881 Campus Commons (8) Reston, VA December 10, 2015 100.0 % $ 65,000 $ 500 Market Square (9) Washington, D.C. October 28, 2015 49.0 % $ 291,600 (9) $ 3,100 11 Property Sale (10) Various (10) July 1, 2015 100.0 % $ 433,300 $ 20,200 (1) Exclusive of transaction costs and price adjustments. (2) Sales price is for the partial interests in the properties that were sold. Columbia Property Trust contributed the 333 Market Street building and the University Circle property to joint ventures, and simultaneously sold a 22.5% interest in those joint ventures for $234.0 million to Allianz, an unrelated third party (collectively, the "San Francisco Joint Ventures"). (3) On February 1, 2018, Allianz acquired another 22.5% interest in each of the San Francisco Joint Ventures at an aggregate price of $235.3 million , thereby reducing Columbia Property Trust's equity interest in each joint venture to 55.0% . These proceeds were used to reduce the balance on the $300 Million Bridge Loan and the Revolving Credit Facility, as described in Note 5, Line of Credit and Notes Payable . (4) Key Center Tower & Marriott were sold in one transaction for $254.5 million of gross proceeds and a $13.0 million , 10 -year accruing note receivable from the principal of the buyer. As a result, Columbia Property Trust has applied the installment method to account for this transaction, and deferred $13.0 million of the total $22.5 million gain on sale. The Key Center Tower and Key Center Marriott generated net income of $14.5 million and $12.1 million for the years ended December 31, 2016 and 2015, respectively; and a net loss of $1.9 million for the first 31 days of 2017, excluding the gain on sale. (5) 5 Houston Center, Energy Center I, and 515 Post Oak were sold in one transaction. These properties generated net income of $11.1 million and $12.9 million for the years ended December 31, 2016 and 2015, respectively; and a net loss of $14.9 thousand for the first six days of 2017, excluding the gain on sale. (6) Columbia Property Trust recorded a de minimus loss on the sale of 9127 South Jamaica Street. (7) The net sale proceeds of $159.4 million from 100 East Pratt were used to repay the $119.0 million remaining on the 2015 Bridge Loan on April 1, 2016. (8) The net proceeds from the sale of 1881 Campus Commons were used to reduce the outstanding balance of the 2015 Bridge Loan. (9) Sale price is for our partial interest in the property. On October 28, 2015, Columbia Property Trust transferred the Market Square properties, valued at $595.0 million and subject to a $325.0 million mortgage note, to a joint venture and sold a 49% interest in that joint venture to Blackstone Property Partners for net proceeds of approximately $120.0 million . Columbia Property Trust retains a 51% interest in the Market Square Joint Venture. See Note 4, Unconsolidated Joint Ventures , for additional information. (10) Columbia Property Trust closed on the sale of 11 properties on July 1, 2015 (the "11 Property Sale"). The 11 Property Sale included 170 and 180 Park Avenue in Northern New Jersey; 1580 West Nursery Road in Baltimore; Acxiom, Highland Landmark III, The Corridors III, 215 Diehl Road, 544 Lakeview, and Bannockburn Lake III in Chicago; and Robbins Road and 550 King Street in Boston. The proceeds for 10 of the properties were available on July 1, 2015, and the remaining proceeds were available on August 3, 2015. For the period from January 1, 2015 through July 1, 2015, the aggregate net income, excluding the gain on sale, for the properties included in the 11 Property Sale was $6.5 million ; and for the year ended December 31, 2015 , the net income for the properties included in the 11 Property Sale was $3.0 million , excluding the gain on sale.

Unconsolidated Joint Ventures (

Unconsolidated Joint Ventures (Tables)	12 Months Ended
	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Summary of Financial Information for the Joint Ventures	As of December 31, 2017 and December 31, 2016 , Columbia Property Trust owns interests in the following properties through joint ventures, which are accounted for using the equity method of accounting: Carrying Value of Investment Joint Venture (1) Property Name Geographic Market Ownership Interest December 31, 2017 December 31, 2016 Market Square Joint Venture Market Square Washington, D.C. 51.0 % $ 128,411 $ 127,346 University Circle Joint Venture University Circle San Francisco 77.5 % (2) 173,798 — 333 Market Street Joint Venture 333 Market Street San Francisco 77.5 % (2) 288,236 — 114 Fifth Avenue Joint Venture 114 Fifth Avenue New York 49.5 % 110,311 — 1800 M Street Joint Venture 1800 M Street Washington, D.C. 55.0 % 242,486 — $ 943,242 $ 127,346 (1) See Note 3, Real Estate Transactions, for a description of the formation of these joint ventures. (2) On February 1, 2018, Allianz acquired from Columbia Property Trust an additional 22.5% interest in each of the University Circle Joint Venture and the 333 Market Street Joint Venture, thereby reducing Columbia Property Trust's equity interest in each joint venture to 55.0% . During the years ended December 31, 2017 , 2016 , and 2015 , Columbia Property Trust earned the following fees from these unconsolidated joint ventures: 2017 2016 2015 Market Square Joint Venture $ 1,998 $ 2,122 $ 213 University Circle Joint Venture 1,000 — — 333 Market Street Joint Venture 367 — — 1800 M Street Joint Venture 417 — — $ 3,782 $ 2,122 $ 213 Summarized balance sheet information for each of the unconsolidated joint ventures is as follows (in thousands): Total Assets Total Debt Total Equity (1) December 31, 2017 December 31, 2016 December 31, 2017 December 31, 2016 December 31, 2017 December 31, 2016 Market Square Joint Venture $ 590,115 $ 587,344 $ 324,708 $ 324,656 $ 244,506 $ 242,802 University Circle Joint Venture 227,368 — — — 221,154 — 333 Market Street Joint Venture 385,297 — — — 368,994 — 114 Fifth Avenue Joint Venture 392,486 — — — 170,525 — 1800 M Street Joint Venture 458,964 — — — 438,227 — $ 2,054,230 $ 587,344 $ 324,708 $ 324,656 $ 1,443,406 $ 242,802 (1) There is an aggregate basis difference of $32.0 million , which represents the differences between the historical costs recorded at the joint venture level, and Columbia Property Trust's investment in the joint ventures and results from differences in the timing of each partner's interest acquisition and formation costs incurred by Columbia Property Trust. The basis difference is being amortized to income (loss) from unconsolidated joint ventures over the lives of the related assets or liabilities. Summarized income statement information for the unconsolidated joint ventures for the years ended December 31, 2017 , 2016 and 2015 is as follows (in thousands): Total Revenues Net Income (Loss) Columbia Property Trust's Share of Net Income (Loss) 2017 2016 2015 2017 2016 2015 2017 2016 2015 Market Square Joint Venture $ 41,749 $ 41,230 $ 7,962 $ (15,192 ) $ (14,825 ) $ (2,239 ) $ (7,747 ) $ (7,561 ) $ (1,142 ) University Circle Joint Venture 19,386 — — 9,826 — — 7,561 — — 333 Market Street Joint Venture 12,971 — — 6,948 — — 5,331 — — 114 Fifth Avenue Joint Venture 20,133 — — (4,885 ) — — (2,820 ) — — 1800 M Street Joint Venture 8,005 — — 619 — — 326 — — $ 102,244 $ 41,230 $ 7,962 $ (2,684 ) $ (14,825 ) $ (2,239 ) $ 2,651 $ (7,561 ) $ (1,142 )

Line of Credit and Notes Paya30

Line of Credit and Notes Payable (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Line of Credit and Notes Payable Indebtedness Outstanding (Excluding Bonds Payable)	As of December 31, 2017 and 2016 , Columbia Property Trust had the following line of credit and notes payable indebtedness outstanding (excluding bonds payable; see Note 6, Bonds Payable ) in thousands: Rate as of Term Debt or Interest Only Outstanding Balance as of December 31, Facility Maturity 2017 2016 $300 Million Term Loan LIBOR + 110 bp (1) Interest only 7/31/2020 $ 300,000 $ 300,000 $300 Million Bridge Loan LIBOR + 110 bp (2) Interest only 11/27/2018 300,000 — Revolving Credit Facility LIBOR + 100 bp (3) Interest only 7/31/2019 152,000 — $150 Million Term Loan LIBOR + 110 bp (4) Interest only 7/29/2022 150,000 150,000 263 Shuman Boulevard Building mortgage note (5) 10.55 % Interest only 7/1/2017 49,000 49,000 One Glenlake Building mortgage note 5.80 % Term debt 12/10/2018 23,176 26,315 650 California Street Building mortgage note 3.60 % Term debt 7/1/2019 — 126,287 221 Main Building mortgage note 3.95 % Interest only 5/10/2017 — 73,000 Less: Deferred financing costs related to term loans, bridge loan, and mortgage notes payable (2,991 ) (3,136 ) Total indebtedness $ 971,185 $ 721,466 (1) The $300 Million Term Loan bears interest, at Columbia Property Trust's option, at LIBOR, plus an applicable margin ranging from 0.90% to 1.75% for LIBOR loans, or an alternate base rate, plus an applicable margin ranging from 0.00% to 0.75% for base-rate loans, based on Columbia Property Trust's applicable credit rating. (2) The $300 Million Bridge Loan bears interest, at Columbia Property Trust's option, at LIBOR, plus an applicable margin ranging from 0.90% to 1.75% for LIBOR loans, or an alternate base rate, plus an applicable margin ranging from 0.00% to 0.75% for base-rate loans, based on Columbia Property Trust's applicable credit rating. (3) Borrowings under the Revolving Credit Facility, as described below, bear interest at the option of Columbia Property Trust at LIBOR, plus an applicable margin ranging from 0.875% to 1.55% for LIBOR-based borrowings, or an alternate base rate, plus an applicable margin ranging from 0.00% to 0.55% for base-rate borrowings, based on Columbia Property Trust's applicable credit rating. (4) Columbia Property Trust is party to an interest rate swap agreement with a notional amount of $150.0 million , which effectively fixes its interest rate on the $150 Million Term Loan, as further described below, at 3.07% and terminates on July 29, 2022. This interest rate swap agreement qualifies for hedge accounting treatment; therefore, changes in the fair value are recorded as a market value adjustment to interest rate swap in the accompanying consolidated statement of other comprehensive income. (5) The OfficeMax lease at 263 Shuman Boulevard expired in May 2017, and the mortgage note matured in July 2017. Columbia Property Trust is working with the special-servicer to effect the transfer of the property to the lender in settlement of the loan principal, accrued interest expense and accrued property operating expenses. In the third and fourth quarters of 2017, Columbia Property Trust accrued related interest expense of $2.6 million at the default rate of 10.55% , and property operating expenses of $0.9 million , primarily related to property taxes and repairs and maintenance.
Aggregate Maturities of Columbia Property Trust's Line of Credit and Notes Payable	The following table summarizes the aggregate maturities of Columbia Property Trust's line of credit and notes payable as of December 31, 2017 (in thousands): 2018 $ 323,176 2019 152,000 2020 300,000 2021 — 2022 150,000 Thereafter — Total (1) $ 925,176 (1) The $49.0 million 263 Shuman mortgage note is excluded from this table. The mortgage note matured in July 2017. Columbia Property Trust is working with the special-servicer to effect the transfer of the property to the lender in settlement of the loan principal, accrued interest expense, and accrued property operating expenses.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	As of December 31, 2017 , the required payments under the terms of the remaining two consolidated ground leases and the corporate office lease are as follows (in thousands): 2018 $ 3,282 2019 3,360 2020 3,382 2021 3,405 2022 3,587 Thereafter 192,352 Total $ 209,368
Schedule of Future Minimum Lease Payments for Capital Leases	The required payments under the terms of the leases are as follows as of December 31, 2017 (in thousands): 2018 $ 7,200 2019 7,200 2020 7,200 2021 127,200 2022 — Thereafter — 148,800 Amounts representing interest (28,800 ) Total $ 120,000

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of the Activity of the Employee Stock Grants	Below is a summary of the shares of stock issued under the LTIP for the years ended December 31, 2017, 2016, and 2015: Shares (in thousands) Weighted-Average, Grant-Date Fair Value (1) Unvested shares as of January 1, 2015 104 $ 24.82 Granted 123 $ 24.40 Vested (74 ) $ 24.60 Forfeited (2 ) $ 24.56 Unvested shares as of December 31, 2015 151 $ 24.59 Granted 247 $ 21.79 Vested (138 ) $ 23.32 Forfeited (4 ) $ 21.90 Unvested shares as of December 31, 2016 256 $ 22.62 Granted 333 $ 21.59 Vested (193 ) $ 22.42 Forfeited (7 ) $ 21.81 Unvested shares as of December 31, 2017 389 (2) $ 21.85 (1) Columbia Property Trust determined the weighted-average grant-date fair value using the market closing price on the date of the grant. (2) As of December 31, 2017 , Columbia Property Trust expects approximately 370,000 of the 389,000 unvested shares to ultimately vest, assuming a forfeiture rate of 5% , which was determined based on peer company data, adjusted for the specifics of the LTIP. A summary of the activity for the Performance-Based RSUs under the LTIP follows: Performance-Based RSU Awards (in thousands) Weighted-Average, Grant-Date Fair Value (1) Unvested performance-based share awards as of December 31, 2016 — $ — Granted 331 $ 18.78 Vested — $ — Forfeited (2 ) $ 19.01 Unvested performance-based share awards as of December 31, 2017 329 (2) $ 18.78 (1) Columbia Property Trust determined the weighted-average grant-date fair value using the estimated fair value on the date of grant. (2) As of December 31, 2017 , Columbia Property Trust expects approximately 303,000 of the 329,000 unvested performance-based restricted share units to ultimately vest, assuming a forfeiture rate of 8% , which was determined based on peer company data, adjusted for the specifics of the LTIP.
Summary of Shares Granted to Independent Directors	A summary of these grants, made under the LTIP, follows: Date of Grant Shares Weighted-Average Grant-Date Fair Value 2017 Director Grants: January 3, 2017 8,279 $ 21.58 May 2, 2017 33,581 $ 22.57 November 27, 2017 (1) 1,596 $ 23.07 2016 Director Grants: January 4, 2016 7,439 $ 23.00 April 1, 2016 8,120 $ 21.89 July 1, 2016 8,158 $ 21.52 October 3, 2016 7,727 $ 22.19 2015 Director Grants: January 2, 2015 5,850 $ 25.75 April 1, 2015 4,995 $ 27.16 July 1, 2015 4,144 $ 24.84 October 1, 2015 4,571 $ 23.40 (1) In November 2017, a new director was appointed to the board of directors of Columbia Property Trust. The new director received a pro-rated annual equity retainer grant at appointment.
Summary of Incurred Stock-Based Compensation Expense	Columbia Property Trust incurred stock-based compensation expense related to the following events (in thousands): 2017 2016 2015 Amortization of unvested LTIP awards $ 4,098 $ 2,856 $ 1,699 Future employee awards (1) 2,509 1,006 1,353 Issuance of shares to independent directors 973 696 496 Total stock-based compensation expense $ 7,580 $ 4,558 $ 3,548 (1) Reflects amortization of LTIP awards for service during the current period, for which shares will be issued in future periods.
Summary of Stock Option Activity Under the Director Plan	A summary of stock option activity under the Director Plan during 2017 , 2016 , and 2015 , follows: Number Exercise Price Exercisable Outstanding as of December 31, 2014 3,875 $ 48.00 3,875 Granted — Expired (2,000 ) Outstanding as of December 31, 2015 1,875 $ 48.00 1,875 Granted — Expired (500 ) Outstanding as of December 31, 2016 1,375 $ 48.00 1,375 Granted — Expired (1,375 ) Outstanding as of December 31, 2017 — $ — —

Operating Leases (Tables)

Operating Leases (Tables)	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Schedule of Future Minimum Payments Receivable for Operating Leases	The future minimum rental income from Columbia Property Trust's investment in real estate assets under noncancelable operating leases, excluding lease incentives, as of December 31, 2017 , is as follows (in thousands): 2018 $ 231,641 2019 247,774 2020 243,053 2021 207,919 2022 192,322 Thereafter 1,440,917 Total $ 2,563,626

Supplemental Disclosure of Nonc

Supplemental Disclosure of Noncash Investing and Financing Activities (Tables)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Schedule of Other Significant Noncash Transactions	Outlined below are significant noncash investing and financing activities for the years ended December 31, 2017 , 2016 , and 2015 (in thousands): Years Ended December 31, 2017 2016 2015 Investment in real estate funded with other assets $ 311 $ 1,442 $ 27,000 Deposits applied to sales of real estate $ 10,000 $ — $ — Other assets assumed upon acquisition $ 1,014 $ — $ 7,785 Other liabilities assumed upon acquisition $ 268 $ — $ 4,765 Real estate assets transferred to unconsolidated joint venture $ 558,122 $ — $ 531,696 Mortgage note transferred to unconsolidated joint venture $ — $ — $ 325,000 Other assets transferred to unconsolidated joint venture $ 43,700 $ — $ 37,987 Other liabilities transferred to unconsolidated joint venture $ 21,347 $ — $ 20,595 Discount on issuance of bonds payable $ — $ 1,309 $ 494 Amortization of discounts (premiums) on debt $ 180 $ 267 $ (18 ) Market value adjustment to interest rate swaps that qualify for hedge accounting treatment $ 1,786 $ 1,553 $ (1,570 ) Accrued capital expenditures and deferred lease costs $ 25,069 $ 15,042 $ 19,324 Accrued dividends payable $ 23,961 $ 36,727 $ 37,354 Common stock issued to employees and directors, and amortized (net of income tax witholdings) $ 5,764 $ 3,388 $ 3,548

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Income Tax Basis Net Income Reconciliation	Columbia Property Trust's income tax basis net income during 2017 , 2016 , and 2015 (in thousands) follows: 2017 2016 2015 GAAP basis financial statement net income attributable to the common stockholders of Columbia Property Trust, Inc. $ 176,041 $ 84,281 $ 44,619 Increase (Decrease) in Net Income Resulting From: Depreciation and amortization expense for financial reporting purposes in excess of amounts for income tax purposes 33,918 34,569 81,559 Rental income accrued for financial reporting purposes in excess of amounts for income tax purposes (38,426 ) (26,900 ) (13,409 ) Net amortization of above-/below-market lease intangibles for financial reporting purposes less than amounts for income tax purposes (6,091 ) (9,013 ) (6,626 ) Gain on interest rate swaps that do not qualify for hedge accounting treatment for financial reporting purposes in excess of amounts for income tax purposes — — (2,633 ) Bad debt expense for financial reporting purposes less than amounts for income tax purposes (31 ) (261 ) 5 Income from unconsolidated joint ventures for financial reporting purchases in excess of amount for income tax purposes 13,902 — — Gains or losses on disposition of real property for financial reporting purposes that are more favorable than amounts for income tax purposes (126,770 ) (71,701 ) (117,857 ) Other expenses for financial reporting purposes in excess of amounts for income tax purposes 11,331 (2,707 ) 14,342 Income tax basis net income, prior to dividends-paid deduction $ 63,874 $ 8,268 $ —
Schedule of Distributions to Common Stockholders	Columbia Property Trust's distributions per common share are summarized as follows: 2017 2016 2015 Ordinary income 58.5 % 5.6 % — % Capital gains — % — % — % Return of capital 41.5 % 94.4 % 100.0 % Total 100.0 % 100.0 % 100.0 %
Schedule of Income Taxes	The income taxes recorded by the TRS Entities for the years ended December 31, 2017 , 2016 , and 2015 , are as follows: Years Ended December 31, 2017 2016 2015 Federal income tax $ 188 $ 255 $ 17 State income tax 38 21 25 Total income tax $ 226 $ 276 $ 42

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Earnings per Share	The following table reconciles the numerator for the basic and diluted earnings-per-share computations shown on the consolidated statements of income (in thousands): 2017 2016 2015 Net income $ 176,041 $ 84,281 $ 44,619 Distributions paid on unvested shares (337 ) (314 ) (185 ) Net income used to calculate basic and diluted earnings per share $ 175,704 $ 83,967 $ 44,434 The following table reconciles the denominator for the basic and diluted earnings-per-share computations shown on the consolidated statements of income (in thousands): 2017 2016 2015 Weighted-average common shares – basic 120,795 123,130 124,757 Plus Incremental Weighted-Average Shares From Time-Vested Conversions Less Assumed Share Repurchases: Previously granted LTIP awards, unvested 116 58 33 Future LTIP awards 248 40 57 Weighted-average common shares – diluted 121,159 123,228 124,847

Quarterly Results (Unaudited) (

Quarterly Results (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	Presented below is a summary of the unaudited quarterly financial information for the years ended December 31, 2017 and 2016 (in thousands, except per-share data): 2017 First Quarter Second Quarter Third Quarter Fourth Quarter Revenues $ 82,156 $ 74,857 $ 60,362 $ 71,625 Net income $ 74,722 (1) $ 1,133 $ 101,534 (2) $ (1,348 ) Net income per share – basic $ 0.61 $ 0.01 $ 0.84 $ (0.01 ) Net income per share – diluted $ 0.61 $ 0.01 $ 0.84 $ (0.01 ) Dividends declared per share $ 0.20 $ 0.20 $ 0.20 $ 0.20 2016 First Quarter Second Quarter Third Quarter Fourth Quarter Revenues $ 126,579 $ 127,930 $ 113,266 $ 105,768 Net income $ 6,697 $ 13,286 (3) $ 36,898 (4) $ 27,400 (5) Net income per share – basic $ 0.05 $ 0.11 $ 0.30 $ 0.22 Net income per share – diluted $ 0.05 $ 0.11 $ 0.30 $ 0.22 Dividends declared per share $ 0.30 $ 0.30 $ 0.30 $ 0.30 (1) Net income for the first quarter of 2017 includes gains on sales of real estate assets of $73.2 million related to the sales of real estate assets as described in Note 3, Real Estate Transactions . (2) Net income for the third quarter of 2017 includes gains on sales of real estate assets of $102.4 million related to the sales of real estate assets as described in Note 3, Real Estate Transactions . (3) Net income for the second quarter of 2016 includes an early termination payment at 222 East 41st Street of $6.2 million . (4) Net income for the third quarter of 2016 includes gains on sales of real estate assets of $50.4 million related to the sales of real estate assets as described in Note 3, Real Estate Transactions ; partially offset by losses on early extinguishment of debt of $18.9 million related to the early repayment of the 2018 Bonds Payable. (5) Net income for the fourth quarter of 2016 includes gains on sales of real estate assets of $22.2 million related to the sales of real estate assets as described in Note 3, Real Estate Transactions .

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Reconciliation of Revenue from Segments to Consolidated	The following table presents property operating revenues by geographic reportable segment (in thousands): For the Years Ended December 31, 2017 2016 2015 New York (1) $ 123,280 $ 117,235 $ 97,643 San Francisco (2) 105,550 109,995 112,696 Atlanta 37,803 36,742 35,715 Washington, D.C. (3) 36,934 33,024 62,766 Boston 11,559 11,796 20,895 Los Angeles 7,462 7,443 7,588 All other office markets 21,460 152,858 207,367 Total office segments 344,048 469,093 544,670 Hotel 1,328 22,958 24,583 Corporate (4) 579 397 267 Total $ 345,955 $ 492,448 $ 569,520 (1) Includes operating revenues for 49.5% of 114 Fifth Avenue based on Columbia Property Trust's ownership interest, from July 6, 2017 through December 31, 2017. These operating revenues are included in equity in income (loss) of unconsolidated joint ventures in the accompanying consolidated statements of operations. (2) Includes operating revenues for 100.0% of 333 Market Street and University Circle through July 5, 2017. Includes operating revenues for 77.5% of 333 Market Street and University Circle based on Columbia Property Trust's ownership interest, from July 6, 2017 through December 31, 2017, which are included in equity in income (loss) of unconsolidated joint ventures in the accompanying consolidated statements of operations. (3) Includes operating revenues for 100.0% of Market Square through October 28, 2015. Includes operating revenues for 51.0% of the Market Square buildings based on Columbia Property Trust's ownership interest, from October 28, 2015 through December 31, 2017; and includes operating revenues for 55.0% of 1800 M Street based on Columbia Property Trust's ownership interest, from October 11, 2017 through December 31, 2017, which are included in equity in income (loss) of unconsolidated joint ventures in the accompanying consolidated statements of operations. (4) The amounts for 2016 and 2015 have been adjusted to conform with 2017 presentation by removing asset and property management fee income. A reconciliation of GAAP revenues to operating revenues is presented below (in thousands): For the Years Ended December 31, 2017 2016 2015 Total revenues $ 289,000 $ 473,543 $ 566,065 Operating revenues included in income (loss) from unconsolidated joint ventures (1) 60,737 21,027 4,060 Asset and property management fee income (2) (3,782 ) (2,122 ) (605 ) Total property operating revenues $ 345,955 $ 492,448 $ 569,520 (1) Columbia Property Trust records its interest in properties held through unconsolidated joint ventures using the equity method of accounting, and reflects its interest in the operating revenues of these properties in income (loss) from unconsolidated joint ventures in the accompanying consolidated statements of operations. (2) See Note 4, Unconsolidated Joint Ventures , of the accompanying consolidated financial statements.
Schedule of Segment Reporting Information, by Segment	A reconciliation of GAAP net income to NOI is presented below (in thousands): For the Years Ended December 31, 2017 2016 2015 Net income $ 176,041 $ 84,281 $ 44,619 Depreciation 80,394 108,543 131,490 Amortization 32,403 56,775 87,128 General and administrative – corporate 34,966 33,876 29,683 General and administrative – joint venture 1,454 — — Real estate acquisition costs — — 3,675 Net interest expense 58,187 67,538 85,265 Interest income from development authority bonds (7,200 ) (7,200 ) (7,200 ) Interest rate swap valuation adjustment — — (2,634 ) Interest expense associated with interest rate swap — — 2,642 Settlement of interest rate swap — — 1,102 Loss on early extinguishment of debt 325 18,997 3,149 Income tax expense (213 ) 445 378 Asset and property management fee income (3,782 ) (2,122 ) (605 ) Adjustments included in loss from unconsolidated joint venture 31,818 17,293 3,134 Gains on sales of real estate assets (175,518 ) (72,325 ) (23,860 ) Net operating income $ 228,875 $ 306,101 $ 357,966 The following table presents net operating income by geographic reportable segment (in thousands): For the Years Ended December 31, 2017 2016 2015 New York (1) $ 73,893 $ 70,038 $ 54,692 San Francisco (2) 76,163 80,529 83,826 Atlanta 33,603 32,939 31,912 Washington, D.C. (3) 18,496 16,372 36,958 Boston 5,380 5,114 12,519 Los Angeles 4,529 4,523 4,853 All other office markets 18,550 92,756 129,199 Total office segments 230,614 302,271 353,959 Hotel (913 ) 3,988 4,593 Corporate (4) (826 ) (158 ) (586 ) Total $ 228,875 $ 306,101 $ 357,966 (1) Includes net operating income for 49.5% of 114 Fifth Avenue based on Columbia Property Trust's ownership interest, from July 6, 2017 through December 31, 2017. This net operating income is included in equity in income (loss) of unconsolidated joint ventures in the accompanying consolidated statements of operations. (2) Includes net operating income for 100.0% of 333 Market Street and University Circle through July 5, 2017. Includes net operating income for 77.5% of 333 Market Street and University Circle based on Columbia Property Trust's ownership interest, from July 6, 2017 through December 31, 2017, which is included in equity in income (loss) of unconsolidated joint ventures in the accompanying consolidated statements of operations. (3) Includes net operating income for 100.0% of Market Square through October 28, 2015. Includes net operating income for 51.0% of the Market Square buildings based on Columbia Property Trust's ownership interest, from October 28, 2015 through December 31, 2017; and includes net operating income for 55.0% of 1800 M Street based on Columbia Property Trust's ownership interest, from October 11, 2017 through December 31, 2017. This net operating income is included in equity in income (loss) of unconsolidated joint ventures in the accompanying consolidated statements of operations. (4) The amounts for 2016 and 2015 have been adjusted to conform with 2017 presentation by removing asset and property management fee income.

Financial Information for Par39

Financial Information for Parent Guarantor, Other Guarantor Subsidiaries, and Non-Guarantor Subsidiaries (Tables)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Consolidating Balance Sheets	Condensed Consolidating Balance Sheets (in thousands) As of December 31, 2017 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Assets: Real Estate Assets, at Cost: Land $ — $ — $ 825,208 $ — $ 825,208 Buildings and improvements, net — 2,110 2,061,309 — 2,063,419 Intangible lease assets, net — — 199,260 — 199,260 Construction in progress — — 44,742 — 44,742 Total real estate assets — 2,110 3,130,519 — 3,132,629 Investment in unconsolidated joint ventures — 943,241 1 — 943,242 Cash and cash equivalents 692 5,079 3,796 — 9,567 Investment in subsidiaries 2,238,577 1,186,594 — (3,425,171 ) — Tenant receivables, net of allowance — 30 2,098 — 2,128 Straight-line rent receivable — — 92,235 — 92,235 Prepaid expenses and other assets 317,364 336,598 19,375 (645,654 ) 27,683 Intangible lease origination costs, net — — 42,959 — 42,959 Deferred lease costs, net — — 141,096 — 141,096 Investment in development authority bonds — — 120,000 — 120,000 Total assets $ 2,556,633 $ 2,473,652 $ 3,552,079 $ (4,070,825 ) $ 4,511,539 Liabilities: Line of credit and notes payable, net $ — $ 899,168 $ 715,327 $ (643,310 ) $ 971,185 Bonds payable, net — 693,756 — — 693,756 Accounts payable, accrued expenses, and accrued capital expenditures 732 10,325 113,949 (4 ) 125,002 Dividends payable 23,961 — — — 23,961 Due to affiliates — — 2,340 (2,340 ) — Deferred income 4 81 18,396 — 18,481 Intangible lease liabilities, net — — 27,218 — 27,218 Obligations under capital leases — — 120,000 — 120,000 Total liabilities 24,697 1,603,330 997,230 (645,654 ) 1,979,603 Equity: Total equity 2,531,936 870,322 2,554,849 (3,425,171 ) 2,531,936 Total liabilities and equity $ 2,556,633 $ 2,473,652 $ 3,552,079 $ (4,070,825 ) $ 4,511,539 Condensed Consolidating Balance Sheets (in thousands) As of December 31, 2016 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Assets: Real Estate Assets, at Cost: Land $ — $ — $ 751,351 $ — $ 751,351 Building and improvements, net — 219 2,120,931 — 2,121,150 Intangible lease assets, net — — 193,311 — 193,311 Construction in progress — — 36,188 — 36,188 Real estate assets held for sale, net — 34,956 377,550 — 412,506 Total real estate assets — 35,175 3,479,331 — 3,514,506 Investment in unconsolidated joint ventures — 127,346 — — 127,346 Cash and cash equivalents 174,420 16,509 25,156 — 216,085 Investment in subsidiaries 2,047,922 1,782,752 — (3,830,674 ) — Tenant receivables, net of allowance — — 7,163 — 7,163 Straight-line rent receivable — — 64,811 — 64,811 Prepaid expenses and other assets 317,153 262,216 15,593 (570,687 ) 24,275 Intangible lease origination costs, net — — 54,279 — 54,279 Deferred lease costs, net — — 125,799 — 125,799 Investment in development authority bonds — — 120,000 — 120,000 Other assets held for sale, net — 3,767 41,814 (52 ) 45,529 Total assets $ 2,539,495 $ 2,227,765 $ 3,933,946 $ (4,401,413 ) $ 4,299,793 Liabilities: Lines of credit and notes payable, net $ — $ 447,643 $ 704,585 $ (430,762 ) $ 721,466 Bonds payable, net — 692,972 — — 692,972 Accounts payable, accrued expenses, and accrued capital expenditures — 10,395 120,633 — 131,028 Dividends payable 36,727 — — — 36,727 Due to affiliates — 58 1,534 (1,592 ) — Deferred income — — 19,694 — 19,694 Intangible lease liabilities, net — — 33,375 — 33,375 Obligations under capital leases — — 120,000 — 120,000 Liabilities held for sale, net — 2,651 177,497 (138,385 ) 41,763 Total liabilities 36,727 1,153,719 1,177,318 (570,739 ) 1,797,025 Equity: Total equity 2,502,768 1,074,046 2,756,628 (3,830,674 ) 2,502,768 Total liabilities and equity $ 2,539,495 $ 2,227,765 $ 3,933,946 $ (4,401,413 ) $ 4,299,793
Consolidating Statements of Operations	Consolidating Statements of Operations (in thousands) For the Year Ended December 31, 2017 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Revenues: Rental income $ — $ 51 $ 257,368 $ (360 ) $ 257,059 Tenant reimbursements — (60 ) 23,571 — 23,511 Hotel income — — 1,339 — 1,339 Asset and property management fee income 1,908 — 1,874 — 3,782 Other property income — — 3,327 (18 ) 3,309 1,908 (9 ) 287,479 (378 ) 289,000 Expenses: Property operating costs — 308 87,857 (360 ) 87,805 Hotel operating costs — — 2,089 — 2,089 Asset and Property Management Fee Expenses: Related-party — 3 — (3 ) — Other — — 918 — 918 Depreciation — 869 79,525 — 80,394 Amortization — 5 32,398 — 32,403 General and administrative – corporate 259 9,048 25,674 (15 ) 34,966 General and administrative – joint ventures — — 1,454 — 1,454 259 10,233 229,915 (378 ) 240,029 1,649 (10,242 ) 57,564 — 48,971 Other Income (Expense): Interest expense — (44,259 ) (38,238 ) 21,981 (60,516 ) Interest and other income 16,535 7,762 7,213 (21,981 ) 9,529 Loss on early extinguishment of debt — — (325 ) — (325 ) 16,535 (36,497 ) (31,350 ) — (51,312 ) Income (loss) before income taxes, unconsolidated entities, and gains on sales of real estate assets 18,184 (46,739 ) 26,214 — (2,341 ) Income tax expense — (1 ) 214 — 213 Income (loss) from unconsolidated entities 157,857 198,620 — (353,826 ) 2,651 Income before gains on sales of real estate assets 176,041 151,880 26,428 (353,826 ) 523 Gains on sales of real estate assets — 11,050 164,468 — 175,518 Net income $ 176,041 $ 162,930 $ 190,896 $ (353,826 ) $ 176,041 Consolidating Statements of Operations (in thousands) For the Year Ended December 31, 2016 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Revenues: Rental income $ — $ 3,622 $ 362,947 $ (383 ) $ 366,186 Tenant reimbursements — 1,963 67,807 — 69,770 Hotel income — — 22,661 — 22,661 Asset and property management fee income 574 — 1,548 — 2,122 Other property income 406 — 12,804 (406 ) 12,804 980 5,585 467,767 (789 ) 473,543 Expenses: Property operating costs — 3,209 152,142 (383 ) 154,968 Hotel operating costs — — 18,686 — 18,686 Asset and Property Management Fee Expenses: Related-party — 154 — (154 ) — Other — — 1,415 — 1,415 Depreciation — 2,760 105,783 — 108,543 Amortization — 364 56,411 — 56,775 General and administrative – corporate 154 8,566 25,408 (252 ) 33,876 154 15,053 359,845 (789 ) 374,263 826 (9,468 ) 107,922 — 99,280 Other Income (Expense): Interest expense — (46,797 ) (50,302 ) 29,490 (67,609 ) Interest and other income 14,268 15,272 7,238 (29,490 ) 7,288 Loss on early extinguishment of debt — (18,987 ) (10 ) — (18,997 ) 14,268 (50,512 ) (43,074 ) — (79,318 ) Income (loss) before income taxes, unconsolidated entities, and gains on sales of real estate assets 15,094 (59,980 ) 64,848 — 19,962 Income tax expense — (20 ) (425 ) — (445 ) Income (loss) from unconsolidated entities 69,187 113,105 — (189,853 ) (7,561 ) Income before gains (loss) on sales of real estate assets 84,281 53,105 64,423 (189,853 ) 11,956 Gains (loss) on sales of real estate assets — — 72,325 — 72,325 Net income $ 84,281 $ 53,105 $ 136,748 $ (189,853 ) $ 84,281 Consolidating Statements of Operations (in thousands) For the Year Ended December 31, 2015 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Revenues: Rental income $ — $ 2,662 $ 433,763 $ (377 ) $ 436,048 Tenant reimbursements — 1,316 98,339 — 99,655 Hotel income — — 24,309 — 24,309 Asset and property management fee income 171 — 434 — 605 Other property income — — 5,781 (333 ) 5,448 171 3,978 562,626 (710 ) 566,065 Expenses: Property operating costs — 3,065 185,390 (377 ) 188,078 Hotel operating costs — — 19,615 — 19,615 Asset and Property Management Fee Expenses: Related-party — 100 — (100 ) — Other — — 1,816 — 1,816 Depreciation — 2,571 128,919 — 131,490 Amortization — 237 86,891 — 87,128 General and administrative – corporate 152 8,754 21,010 (233 ) 29,683 Acquisition expenses — 11 3,664 — 3,675 152 14,738 447,305 (710 ) 461,485 19 (10,760 ) 115,321 — 104,580 Other Income (Expense): Interest expense — (44,919 ) (67,076 ) 26,699 (85,296 ) Interest and other income 14,141 12,565 7,247 (26,699 ) 7,254 Loss on interest rate swaps — (1,101 ) (9 ) — (1,110 ) Loss on early extinguishment of debt — (1,050 ) (2,099 ) — (3,149 ) 14,141 (34,505 ) (61,937 ) — (82,301 ) Income before income taxes, unconsolidated entities, and gains on sales of real estate assets 14,160 (45,265 ) 53,384 — 22,279 Income tax expense — (25 ) (353 ) — (378 ) Income (loss) from unconsolidated entities 30,459 59,165 — (90,766 ) (1,142 ) Income before gains on sales of real estate assets 44,619 13,875 53,031 (90,766 ) 20,759 Gains on sales of real estate assets — (19 ) 23,879 — 23,860 Net income $ 44,619 $ 13,856 $ 76,910 $ (90,766 ) $ 44,619
Consolidating Statements Comprehensive Income	Consolidating Statements of Comprehensive Income (in thousands) For the Year Ended December 31, 2017 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Net income $ 176,041 $ 162,930 $ 190,896 $ (353,826 ) $ 176,041 Market value adjustment to interest rate swap 1,786 1,786 — (1,786 ) 1,786 Comprehensive income $ 177,827 $ 164,716 $ 190,896 $ (355,612 ) $ 177,827 For the Year Ended December 31, 2016 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Net income $ 84,281 $ 53,105 $ 136,748 $ (189,853 ) $ 84,281 Market value adjustment to interest rate swap 1,553 1,553 — (1,553 ) 1,553 Comprehensive income $ 85,834 $ 54,658 $ 136,748 $ (191,406 ) $ 85,834 For the Year Ended December 31, 2015 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Net income $ 44,619 $ 13,856 $ 76,910 $ (90,766 ) $ 44,619 Market value adjustment to interest rate swap (1,570 ) (1,570 ) — 1,570 (1,570 ) Settlement of interest rate swap 1,102 1,102 — (1,102 ) 1,102 Comprehensive income $ 44,151 $ 13,388 $ 76,910 $ (90,298 ) $ 44,151
Consolidating Statements Cash Flows	Consolidating Statements of Cash Flows (in thousands) For the Year Ended December 31, 2017 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Cash flows from operating activities $ 3,966 $ (46,268 ) $ 104,226 $ — $ 61,924 Cash Flows From Investing Activities: Net proceeds from the sale of real estate — 49,531 688,100 — 737,631 Investment in real estate and related assets — (2,203 ) (716,093 ) — (718,296 ) Investment in unconsolidated joint ventures — (369,043 ) — — (369,043 ) Distributions in excess of earnings from unconsolidated joint ventures — 1,985 — — 1,985 Investments in subsidiaries (8,671 ) (97,505 ) — 106,176 — Net cash provided by (used in) investing activities (8,671 ) (417,235 ) (27,993 ) 106,176 (347,723 ) Cash Flows From Financing Activities: Borrowings, net of fees — 781,731 — — 781,731 Repayments — (331,000 ) (202,427 ) — (533,427 ) Redemptions of common stock (59,462 ) — — — (59,462 ) Distributions (109,561 ) 1,342 104,834 (106,176 ) (109,561 ) Net cash provided by (used in) financing activities (169,023 ) 452,073 (97,593 ) (106,176 ) 79,281 Net decrease in cash and cash equivalents (173,728 ) (11,430 ) (21,360 ) — (206,518 ) Cash and cash equivalents, beginning of period 174,420 16,509 25,156 — 216,085 Cash and cash equivalents, end of period $ 692 $ 5,079 $ 3,796 $ — $ 9,567 Consolidating Statements of Cash Flows (in thousands) For the Year Ended December 31, 2016 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Cash flows from operating activities $ 53,980 $ 86,846 $ 242,118 $ (189,853 ) $ 193,091 Cash Flows From Investing Activities: Net proceeds from the sale of real estate (1) — — 613,732 — 613,732 Investment in real estate and related assets — (2,157 ) (69,750 ) — (71,907 ) Investment in unconsolidated joint ventures — (16,212 ) — — (16,212 ) Distributions from subsidiaries (2) 321,911 568,480 — (890,391 ) — Net cash provided by investing activities 321,911 550,111 543,982 (890,391 ) 525,613 Cash Flows From Financing Activities: Borrowings, net of fees (3) — 780,577 — — 780,577 Repayments (4) — (1,051,000 ) (44,460 ) — (1,095,460 ) Prepayments to settle debt and interest rate swap (5) — (17,921 ) — — (17,921 ) Redemptions of common stock (53,986 ) — — — (53,986 ) Distributions (6) (148,474 ) (347,073 ) (733,171 ) 1,080,244 (148,474 ) Net cash used in financing activities (202,460 ) (635,417 ) (777,631 ) 1,080,244 (535,264 ) Net increase in cash and cash equivalents 173,431 1,540 8,469 — 183,440 Cash and cash equivalents, beginning of period 989 14,969 16,687 — 32,645 Cash and cash equivalents, end of period $ 174,420 $ 16,509 $ 25,156 $ — $ 216,085 (1) Net proceeds from the sale of real estate increased (decreased) by $(603.7) million and $603.7 million for the parent and non-guarantors, respectively. (2) Distributions from subsidiaries increased (decreased) by $321.9 million , $568.5 million , and $(890.4) million for the parent, issuer, and eliminations, respectively. (3) Borrowings, net of fees, increased (decreased) by $(781.4) million and $781.4 million for the parent and issuer, respectively. (4) Repayments increased (decreased) by $1,090.0 million , $(1,051.0) million , and $(39.0) million for the parent, issuer, and non-guarantors respectively. (5) Prepayments to settle debt and interest rate swap increased (decreased) by $17.9 million and $(17.9) million for the parent and issuer, respectively. (6) Distributions (increased) decreased by $(347.1) million , $(733.2) million , and $1,080.3 million , for the issuer, non-guarantors, and eliminations, respectively. The intercompany transfers, net line item is no longer presented based on the changes to the other line items described herein. For the Year Ended December 31, 2015 Columbia Property Trust Columbia Property Trust OP Non- Guarantors Consolidating Adjustments Columbia Property Trust Cash flows from operating activities $ 15,743 $ (50,601 ) $ 273,655 $ (15,717 ) $ 223,080 Cash Flows From Investing Activities: Net proceeds from the sale of real estate (1) — — 596,734 — 596,734 Investments in real estate and related assets (2) — — (1,167,933 ) — (1,167,933 ) Investment in unconsolidated joint ventures — (5,500 ) — — (5,500 ) Investments in subsidiaries (3) (4,615 ) (628,393 ) — 633,008 — Net cash used in investing activities (4,615 ) (633,893 ) (571,199 ) 633,008 (576,699 ) Cash Flows From Financing Activities: Borrowings, net of fees (3) — 2,223,778 — — 2,223,778 Repayments — (1,518,000 ) (336,512 ) — (1,854,512 ) Prepayments to settle debt and interest rate swap — (1,102 ) (2,063 ) — (3,165 ) Redemptions of common stock (17,057 ) — — — (17,057 ) Distributions (4) (112,570 ) (15,717 ) 633,008 (617,291 ) (112,570 ) Net cash provided by (used in) financing activities (129,627 ) 688,959 294,433 (617,291 ) 236,474 Net increase (decrease) in cash and cash equivalents (118,499 ) 4,465 (3,111 ) — (117,145 ) Cash and cash equivalents, beginning of period 119,488 10,504 19,798 — 149,790 Cash and cash equivalents, end of period $ 989 $ 14,969 $ 16,687 $ — $ 32,645 (1) Net proceeds from the sales of real estate increased (decreased) by $(72.4) million , $(524.4) million , and $596.7 million for the parent, issuer, and non-guarantors, respectively. (2) Investments in real estate and related assets increased (decrease) by $57.2 million , $1,007.5 million , and $(1,064.7) million for the parent, issuer, and non-guarantors, respectively. (3) Investments in subsidiaries increased (decreased) by $1,061.1 million , $(628.4) million , and $(432.7) million for the parent, issuer, and eliminations, respectively. (4) Distributions (increased) decreased by $(15.7) million , $633.0 million , and $(617.3) million , for the issuer, non-guarantors, and eliminations, respectively. The intercompany transfers, net line item is no longer presented based on the changes to the other line items described herein.

Organization (Details)

Organization (Details) ft² in Millions	Dec. 31, 2017ft²property
Real Estate
Square feet of commercial space | ft²	9.2
Leased office space of owned properties, percent	96.20%
Office Building
Real Estate
Number of properties	19
Office Building | Wholly Owned Properties
Real Estate
Number of properties	14
Office Building | Corporate Joint Venture
Real Estate
Number of properties	5

Summary of Significant Accoun41

Summary of Significant Accounting Policies (Narrative) (Details) - USD ($)	Aug. 12, 2016	Aug. 31, 2016	Jul. 31, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2018
Property, Plant and Equipment [Line Items]
Interest capitalized						$ 700,000	$ 300,000	$ 600,000
Accumulated depreciation of lease assets					$ 94,065,000	94,065,000	112,777,000
Amortization of intangible assets						$ 31,907,000	52,530,000	78,000,000
Cash equivalent maturity period						3 months
Provision for doubtful accounts						$ 26,000	289,000
Amortization of deferred leasing costs						5,200,000	9,300,000	8,900,000
Amortization of lease incentives						$ 3,300,000	3,900,000	3,700,000
Lease term						30 years
Reclassified deferred financing costs					$ 2,991,000	$ 2,991,000	$ 3,136,000
Common stock, par value (in dollars per share)					$ 0.01	$ 0.01	$ 0.01
Preferred stock shares authorized					100,000,000	100,000,000
Preferred stock par value (in dollars per share)					$ 0.01	$ 0.01
Minimum requirement to distribute taxable income (percent)					90.00%	90.00%
Loans payable					$ 971,185,000	$ 971,185,000	$ 721,466,000
Proceeds from master leases						$ 0	0	0
Limit on investments in taxable real estate investment trusts (percent)					25.00%	25.00%
Property management fee revenue and parking agreement revenue						$ 6,700,000	$ 3,600,000	$ 1,800,000
Property management fee revenue and parking agreement revenue as a percentage of total revenue						2.30%	0.80%	0.30%
Lease revenue						$ 281,000,000	$ 447,300,000	$ 539,900,000
Lease revenue as a percentage of total revenue						97.20%	94.50%	95.40%
Intangible below market ground lease assets
Property, Plant and Equipment [Line Items]
Gross intangible assets					$ 140,900,000	$ 140,900,000	$ 140,900,000
Accumulated depreciation of lease assets					22,800,000	22,800,000	20,200,000
Amortization of intangible assets						$ 2,500,000	2,500,000	$ 2,500,000
Building | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life of assets						40 years
Building | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of assets						45 years
Building and site improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life of assets						5 years
Building and site improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of assets						25 years
222 East 41st Street
Property, Plant and Equipment [Line Items]
Leasehold improvements					54,700,000	$ 54,700,000	69,000,000
Lease term						30 years
222 East 41st Street | Unamortized lease incentives
Property, Plant and Equipment [Line Items]
Gross intangible assets					68,400,000	$ 68,400,000	69,000,000
Term Loans
Property, Plant and Equipment [Line Items]
Reclassified deferred financing costs					2,991,000	2,991,000	3,136,000
Term Loans | $450 Million Term Loan
Property, Plant and Equipment [Line Items]
Loans payable			$ 450,000,000
Bonds Payable
Property, Plant and Equipment [Line Items]
Reclassified deferred financing costs					$ 4,760,000	$ 4,760,000	5,364,000
Bonds Payable | 2026 Bonds Payable
Property, Plant and Equipment [Line Items]
Debt face amount	$ 350,000,000	$ 350,000,000
Debt term	10 years	10 years
Stated interest rate	3.65%	3.65%
Discount rate of face value of issued debt instrument (percent)	99.626%	99.626%
Bonds Payable | 2025 Bonds Payable
Property, Plant and Equipment [Line Items]
Debt face amount				$ 350,000,000
Debt term				10 years
Stated interest rate				4.15%
Discount rate of face value of issued debt instrument (percent)				99.859%
Common Stock | Stock Repurchase Program
Property, Plant and Equipment [Line Items]
Common stock, par value (in dollars per share)					$ 0.01	$ 0.01
Stock repurchase program, amount available for repurchase					$ 194,800,000	$ 194,800,000
Interest Rate Swap
Property, Plant and Equipment [Line Items]
Payment to settle interest rate swap			$ 1,100,000
Interest Expense
Property, Plant and Equipment [Line Items]
Amortization of deferred financing costs						$ 2,800,000	$ 3,300,000	$ 4,400,000
ASU 2017-05
Property, Plant and Equipment [Line Items]
Cumulative effect of new accounting principle in period of adoption									$ 357,800,000
Early adoption | ASU 2017-01
Property, Plant and Equipment [Line Items]
Transaction costs capitalized					$ 2,200,000

Summary of Significant Accoun42

Summary of Significant Accounting Policies (Major Classes of Assets and Liabilities Held For Sale) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other Assets Held for Sale:
Total other assets held for sale, net	$ 0	$ 45,529
Liabilities Held for Sale:
Total liabilities held for sale, net	$ 0	41,763
Held-for-sale | Key Center Tower, Key Center Marriott, 5 Houston Center, Energy Center I, and 515 Post Oak
Real Estate Assets, at Cost:
Land		30,243
Buildings and improvements, less accumulated depreciation of $152,246		366,126
Intangible lease assets, less accumulated amortization of $28,545		13,365
Construction in progress		2,772
Total real estate assets held for sale, net		412,506
Other Assets Held for Sale:
Tenant receivables, net of allowance for doubtful accounts		1,722
Straight-line rent receivable		20,221
Prepaid expenses and other assets		3,184
Intangible lease origination costs, less accumulated amortization of $22,949		1,815
Deferred lease costs, less accumulated amortization of $11,203		18,587
Total other assets held for sale, net		45,529
Liabilities Held for Sale:
Accounts payable, accrued expenses, and accrued capital expenditures		34,812
Deferred income		4,214
Intangible lease liabilities, less accumulated amortization of $1,239		2,737
Total liabilities held for sale, net		41,763
Accumulated depreciation for buildings and improvements held for sale		152,246
Accumulated amortization for intangible lease assets held for sale		28,545
Accumulated amortization for lease origination costs held for sale		22,949
Accumulated amortization for deferred lease costs held for sale		11,203
Accumulated amortization for intangible lease liabilities held for sale		$ 1,239

Summary of Significant Accoun43

Summary of Significant Accounting Policies (Schedule of Intangible Assets & Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Intangible Lease Assets
Intangible lease assets, accumulated amortization	$ (94,065)	$ (112,777)
Intangible lease origination costs, accumulated amortization	(57,465)	(74,578)
Intangible lease assets, net	199,260	193,311
Intangible lease origination costs, net	42,959	54,279
Intangible Below-Market In-Place Lease Liabilities
Intangible below-market in-place lease liabilities, gross	46,878	77,939
Intangible below-market in-place lease liabilities, accumulated amortization	(19,660)	(44,564)
Below market lease, net	27,218	33,375
Amortization of below market lease liabilities	6,883	12,996	$ 19,345
Above-Market In-Place Lease Assets
Intangible Lease Assets
Intangible lease assets, gross	2,481	10,589
Intangible lease assets, accumulated amortization	(833)	(9,305)
Intangible lease assets, net	1,648	1,284
Amortization of intangible lease assets	519	2,513	4,412
Absorption Period Costs
Intangible Lease Assets
Intangible lease assets, gross	149,927	154,582
Intangible lease assets, accumulated amortization	(70,465)	(83,254)
Intangible lease assets, net	79,462	71,328
Amortization of intangible lease assets	16,807	28,718	45,972
Intangible Lease Origination Costs
Intangible Lease Assets
Intangible lease origination costs, gross	100,424	128,857
Intangible lease origination costs, accumulated amortization	(57,465)	(74,578)
Intangible lease origination costs, net	42,959	54,279
Amortization of intangible lease assets	$ 10,124	$ 17,501	$ 28,530

Summary of Significant Accoun44

Summary of Significant Accounting Policies (Schedule of Future Amortization by Intangible Asset Class) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Intangible Lease Assets
Intangible lease assets, net	$ 199,260	$ 193,311
Intangible lease origination costs, net	42,959	54,279
Intangible Below-Market In-Place Lease Liabilities
2,018	6,325
2,019	5,968
2,020	4,535
2,021	1,591
2,022	1,287
Thereafter	7,512
Below market lease, net	$ 27,218	33,375
Weighted-average amortization period	6 years
Above-Market In-Place Lease Assets
Intangible Lease Assets
2,018	$ 203
2,019	203
2,020	203
2,021	203
2,022	203
Thereafter	633
Intangible lease assets, net	$ 1,648	1,284
Weighted-average amortization period	8 years
Absorption Period Costs
Intangible Lease Assets
2,018	$ 16,898
2,019	14,665
2,020	12,800
2,021	8,112
2,022	6,585
Thereafter	20,402
Intangible lease assets, net	$ 79,462	71,328
Weighted-average amortization period	5 years
Intangible Lease Origination Costs
Intangible Lease Assets
2,018	$ 9,566
2,019	8,651
2,020	7,770
2,021	3,727
2,022	2,708
Thereafter	10,537
Intangible lease origination costs, net	$ 42,959	$ 54,279
Weighted-average amortization period	5 years

Summary of Significant Accoun45

Summary of Significant Accounting Policies (Schedule of Future Amortization for Below-Market Lease Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Intangible Lease Assets
Intangible lease assets, net	$ 199,260	$ 193,311
Intangible below market ground lease assets
Intangible Lease Assets
2,018	2,549
2,019	2,549
2,020	2,549
2,021	2,549
2,022	2,549
Thereafter	105,405
Intangible lease assets, net	$ 118,150
Weighted-average amortization period	47 years

Summary of Significant Accoun46

Summary of Significant Accounting Policies (Interest Rate Swaps) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of Derivative Instruments Impact on Results of Operations [Abstract]
Market value adjustment to interest rate swaps designated as hedging instruments and included in other comprehensive income	$ 1,786	$ 1,553	$ (1,570)
Loss on interest rate swap recognized through earnings	0	0	$ (1,110)
Interest Rate Contract | Prepaid Expenses and Other Assets
Derivative, Fair Value, Net [Abstract]
Derivative designated as hedging instruments, interest rate contracts	903	0
Interest Rate Contract | Accounts Payable
Derivative, Fair Value, Net [Abstract]
Derivative designated as hedging instruments, interest rate contracts	$ 0	$ (882)

Real Estate Transactions (Sched

Real Estate Transactions (Schedule of Properties Acquired) (Details) - USD ($) $ in Thousands	Nov. 28, 2017	Oct. 11, 2017	Jul. 06, 2017	Aug. 04, 2015	Jan. 08, 2015	Jan. 07, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Purchase price							$ 604,769	$ 0	$ 1,062,031
Purchase price							$ 369,043	$ 16,212	$ 5,500
149 Madison Avenue
Business Acquisition [Line Items]
Ownership percentage	100.00%
Purchase price	$ 87,700
245-249 West 17th Street & 218 West 18th Street
Business Acquisition [Line Items]
Ownership percentage		100.00%
Purchase price		$ 514,100
229 West 43rd Street
Business Acquisition [Line Items]
Ownership percentage				100.00%
Purchase price				$ 516,000
116 Huntington Avenue
Business Acquisition [Line Items]
Ownership percentage					100.00%
Purchase price					$ 152,000
315 Park Avenue South & 1881 Campus Commons
Business Acquisition [Line Items]
Ownership percentage						100.00%
Purchase price						$ 436,000
1800 M Street Joint Venture | Corporate Joint Venture
Business Acquisition [Line Items]
Ownership percentage		55.00%
Purchase price		$ 421,000
Purchase price		$ 231,550
114 Fifth Avenue | Corporate Joint Venture
Business Acquisition [Line Items]
Ownership percentage			49.50%
Purchase price			$ 108,900

Real Estate Transactions (Acqui

Real Estate Transactions (Acquisitions) (Details) ft² in Thousands

Nov. 28, 2017USD ($)ft²

Oct. 11, 2017USD ($)ft²Tenant

Aug. 04, 2015USD ($)ft²Tenant

Jan. 08, 2015USD ($)ft²Tenant

Jan. 07, 2015USD ($)ft²TenantAsset

Dec. 31, 2017USD ($)ft²property

Dec. 31, 2017USD ($)ft²property

Dec. 31, 2015USD ($)

Dec. 31, 2017USD ($)ft²property

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Dec. 31, 2015USD ($)

Dec. 31, 2015USD ($)

Jul. 06, 2017ft²

Oct. 28, 2015

Business Acquisition [Line Items]

Square feet of space | ft²

9,200

9,200

9,200

Payments to acquire real estate

$ 604,769,000

$ 0

$ 1,062,031,000

Acquisition expenses

$ 0

$ 0

$ 3,675,000

149 Madison Avenue

Business Acquisition [Line Items]

Revenue of acquiree since acquisition date

$ 10,300

Earnings (loss) of acquiree since acquisition date

$ 9,200

Payments to acquire real estate

$ 87,700,000

Ownership percentage

100.00%

245-249 West 17th Street

Business Acquisition [Line Items]

Revenue of acquiree since acquisition date

$ 5,900,000

Earnings (loss) of acquiree since acquisition date

1,800,000

Percent leased

100.00%

Number of tenants | Tenant

4

218 West 18th Street

Business Acquisition [Line Items]

Revenue of acquiree since acquisition date

3,000,000

Earnings (loss) of acquiree since acquisition date

$ 800,000

Percent leased

100.00%

Number of tenants | Tenant

7

229 West 43rd Street

Business Acquisition [Line Items]

Square feet of space | ft²

732

Revenue of acquiree since acquisition date

$ 15,300,000

Earnings (loss) of acquiree since acquisition date

2,200,000

Percent leased

98.00%

Payments to acquire real estate

$ 516,000,000

Number of tenants | Tenant

9

Acquisition expenses

$ 1,700,000

116 Huntington Avenue

Business Acquisition [Line Items]

Revenue of acquiree since acquisition date

$ 11,300,000

Earnings (loss) of acquiree since acquisition date

(700,000)

Percent leased

78.00%

Payments to acquire real estate

$ 152,000,000

Number of tenants | Tenant

17

Acquisition expenses

$ 300,000

315 Park Avenue South & 1881 Campus Commons

Business Acquisition [Line Items]

Payments to acquire real estate

$ 436,000,000

Ownership percentage

100.00%

315 Park Avenue South Building

Business Acquisition [Line Items]

Revenue of acquiree since acquisition date

$ 25,100,000

Earnings (loss) of acquiree since acquisition date

(6,600,000)

Percent leased

94.90%

Number of tenants | Tenant

9

Acquisition expenses

1,200,000

1881 Campus Commons

Business Acquisition [Line Items]

Revenue of acquiree since acquisition date

5,800,000

Earnings (loss) of acquiree since acquisition date

(1,300,000)

Percent leased

78.00%

Number of tenants | Tenant

15

Acquisition expenses

$ 500,000

Office Building

Business Acquisition [Line Items]

Number of properties | property

19

19

19

Office Building | 149 Madison Avenue

Business Acquisition [Line Items]

Square feet of space | ft²

127

Office Building | 245-249 West 17th Street

Business Acquisition [Line Items]

Square feet of space | ft²

281

Office Building | 218 West 18th Street

Business Acquisition [Line Items]

Square feet of space | ft²

166

Office Building | 229 West 43rd Street

Business Acquisition [Line Items]

Square feet of space | ft²

481

Office Building | 116 Huntington Avenue

Business Acquisition [Line Items]

Square feet of space | ft²

271

Office Building | 315 Park Avenue South & 1881 Campus Commons

Business Acquisition [Line Items]

Number of properties | Asset

2

Office Building | 315 Park Avenue South Building

Business Acquisition [Line Items]

Square feet of space | ft²

327

Office Building | 1881 Campus Commons

Business Acquisition [Line Items]

Square feet of space | ft²

244

Customer concentration risk | Twitter | 245-249 West 17th Street

Business Acquisition [Line Items]

Concentration risk percentage

76.00%

Customer concentration risk | Room & Board | 245-249 West 17th Street

Business Acquisition [Line Items]

Concentration risk percentage

21.00%

Customer concentration risk | Red Bull North America | 218 West 18th Street

Business Acquisition [Line Items]

Concentration risk percentage

25.00%

Customer concentration risk | Company 3 | 218 West 18th Street

Business Acquisition [Line Items]

Concentration risk percentage

18.00%

Customer concentration risk | SY Partners | 218 West 18th Street

Business Acquisition [Line Items]

Concentration risk percentage

16.00%

Customer concentration risk | SAE | 218 West 18th Street

Business Acquisition [Line Items]

Concentration risk percentage

16.00%

Customer concentration risk | Yahoo! | 229 West 43rd Street

Business Acquisition [Line Items]

Concentration risk percentage

40.00%

Customer concentration risk | Snapchat | 229 West 43rd Street

Business Acquisition [Line Items]

Concentration risk percentage

13.00%

Customer concentration risk | Collective, Inc. | 229 West 43rd Street

Business Acquisition [Line Items]

Concentration risk percentage

12.00%

Customer concentration risk | MongoDB | 229 West 43rd Street

Business Acquisition [Line Items]

Concentration risk percentage

10.00%

Customer concentration risk | American Tower | 116 Huntington Avenue

Business Acquisition [Line Items]

Concentration risk percentage

21.00%

Customer concentration risk | GE Healthcare | 116 Huntington Avenue

Business Acquisition [Line Items]

Concentration risk percentage

13.00%

Customer concentration risk | Brigham and Women's | 116 Huntington Avenue

Business Acquisition [Line Items]

Concentration risk percentage

12.00%

Customer concentration risk | Credit Suisse | 315 Park Avenue South Building

Business Acquisition [Line Items]

Concentration risk percentage

74.00%

Customer concentration risk | SOS International | 1881 Campus Commons

Business Acquisition [Line Items]

Concentration risk percentage

15.00%

Customer concentration risk | Siemens | 1881 Campus Commons

Business Acquisition [Line Items]

Concentration risk percentage

12.00%

1800 M Street Joint Venture | Corporate Joint Venture

Business Acquisition [Line Items]

Percent leased

94.00%

Payments to acquire real estate

$ 421,000,000

Ownership percentage

55.00%

1800 M Street Joint Venture | Corporate Joint Venture | Office Building

Business Acquisition [Line Items]

Square feet of space | ft²

581

114 Fifth Avenue | Corporate Joint Venture

Business Acquisition [Line Items]

Ownership percentage

49.50%

Allianz | 1800 M Street Joint Venture | Corporate Joint Venture

Business Acquisition [Line Items]

Ownership percentage

45.00%

Corporate Joint Venture

Business Acquisition [Line Items]

Ownership percentage

51.00%

Corporate Joint Venture | 1800 M Street Joint Venture

Business Acquisition [Line Items]

Ownership percentage

55.00%

55.00%

55.00%

Corporate Joint Venture | 114 Fifth Avenue

Business Acquisition [Line Items]

Square feet of space | ft²

352

Percent leased

100.00%

Ownership percentage

49.50%

49.50%

49.50%

49.50%

Corporate Joint Venture | Allianz | 114 Fifth Avenue

Business Acquisition [Line Items]

Ownership percentage

49.50%

Corporate Joint Venture | L & L Holding Company | 114 Fifth Avenue

Business Acquisition [Line Items]

Ownership percentage

1.00%

Real Estate Transactions (Purch

Real Estate Transactions (Purchase Price Allocation) (Details) - USD ($) $ in Thousands	Nov. 28, 2017	Oct. 11, 2017	Aug. 04, 2015	Jan. 08, 2015	Jan. 07, 2015
149 Madison Avenue
Business Acquisition [Line Items]
Land	$ 59,112
Building and improvements	28,989
Intangible below market lease liability	0
Total purchase price	88,101
245-249 West 17th Street
Business Acquisition [Line Items]
Land		$ 113,149
Building and improvements		194,109
Intangible below market lease liability		(7,131)
Total purchase price		340,597
218 West 18th Street
Business Acquisition [Line Items]
Land		43,836
Building and improvements		126,957
Intangible below market lease liability		(11,757)
Total purchase price		175,324
229 West 43rd Street
Business Acquisition [Line Items]
Land			$ 207,233
Building and improvements			265,952
Intangible below market lease liability			0
Total purchase price			510,283
116 Huntington Avenue
Business Acquisition [Line Items]
Land				$ 0
Building and improvements				108,383
Intangible below market lease liability				(1,878)
Total purchase price				147,325
315 Park Avenue South
Business Acquisition [Line Items]
Land					$ 119,633
Building and improvements					232,598
Intangible below market lease liability					(7,487)
Total purchase price					365,804
1881 Campus Commons
Business Acquisition [Line Items]
Land					7,179
Building and improvements					49,273
Intangible below market lease liability					(97)
Total purchase price					62,601
Intangible lease assets | 149 Madison Avenue
Business Acquisition [Line Items]
Intangible lease assets	0
Intangible lease assets | 245-249 West 17th Street
Business Acquisition [Line Items]
Intangible lease assets		27,408
Intangible lease assets | 218 West 18th Street
Business Acquisition [Line Items]
Intangible lease assets		12,120
Intangible lease assets | 229 West 43rd Street
Business Acquisition [Line Items]
Intangible lease assets			27,039
Intangible lease assets | 116 Huntington Avenue
Business Acquisition [Line Items]
Intangible lease assets				7,907
Intangible lease assets | 315 Park Avenue South
Business Acquisition [Line Items]
Intangible lease assets					16,912
Intangible lease assets | 1881 Campus Commons
Business Acquisition [Line Items]
Intangible lease assets					4,643
Intangible below market ground lease assets | 149 Madison Avenue
Business Acquisition [Line Items]
Intangible lease assets	0
Intangible below market ground lease assets | 245-249 West 17th Street
Business Acquisition [Line Items]
Intangible lease assets		0
Intangible below market ground lease assets | 218 West 18th Street
Business Acquisition [Line Items]
Intangible lease assets		0
Intangible below market ground lease assets | 229 West 43rd Street
Business Acquisition [Line Items]
Intangible lease assets			0
Intangible below market ground lease assets | 116 Huntington Avenue
Business Acquisition [Line Items]
Intangible lease assets				30,244
Intangible below market ground lease assets | 315 Park Avenue South
Business Acquisition [Line Items]
Intangible lease assets					0
Intangible below market ground lease assets | 1881 Campus Commons
Business Acquisition [Line Items]
Intangible lease assets					0
Intangible lease origination costs | 149 Madison Avenue
Business Acquisition [Line Items]
Intangible lease assets	$ 0
Intangible lease origination costs | 245-249 West 17th Street
Business Acquisition [Line Items]
Intangible lease assets		13,062
Intangible lease origination costs | 218 West 18th Street
Business Acquisition [Line Items]
Intangible lease assets		$ 4,168
Intangible lease origination costs | 229 West 43rd Street
Business Acquisition [Line Items]
Intangible lease assets			$ 10,059
Intangible lease origination costs | 116 Huntington Avenue
Business Acquisition [Line Items]
Intangible lease assets				$ 2,669
Intangible lease origination costs | 315 Park Avenue South
Business Acquisition [Line Items]
Intangible lease assets					4,148
Intangible lease origination costs | 1881 Campus Commons
Business Acquisition [Line Items]
Intangible lease assets					$ 1,603

Real Estate Transactions (Pro F

Real Estate Transactions (Pro Forma) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisitions and Dispositions [Abstract]
Revenues	$ 319,064	$ 511,306	$ 582,699
Net income	$ 183,318	$ 93,537	$ 46,363
Net income per share - basic (in dollars per share)	$ 1.51	$ 0.76	$ 0.37
Net income per share - diluted (in dollars per share)	$ 1.51	$ 0.76	$ 0.37

Real Estate Transactions (Dispo

Real Estate Transactions (Dispositions) (Details)

Feb. 01, 2018USD ($)

Jul. 06, 2017USD ($)

Jan. 31, 2017USD ($)

Jan. 06, 2017USD ($)

Jan. 06, 2017USD ($)

Dec. 15, 2016USD ($)

Nov. 30, 2016USD ($)

Oct. 12, 2016USD ($)

Sep. 30, 2016USD ($)

Sep. 22, 2016USD ($)

Jul. 08, 2016USD ($)

Apr. 01, 2016USD ($)

Mar. 31, 2016USD ($)

Dec. 10, 2015USD ($)

Oct. 28, 2015USD ($)

Jul. 01, 2015USD ($)property

Jan. 31, 2017USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Jun. 30, 2015USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Oct. 11, 2017

Business Acquisition [Line Items]

Net proceeds from the sale of real estate

$ 737,631,000

$ 603,732,000

$ 596,734,000

Key Center Tower & Marriot

Business Acquisition [Line Items]

Gain (Loss) on Sale

$ 22,500,000

100 East Pratt

Business Acquisition [Line Items]

Net proceeds from the sale of real estate

$ 159,400,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations

Business Acquisition [Line Items]

Gain (Loss) on Sale

$ 22,200,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations | University Circle & 333 Market Street

Business Acquisition [Line Items]

% Sold

22.50%

Sales Price

$ 234,000,000

Gain (Loss) on Sale

$ 102,400,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations | Key Center Tower & Marriot

Business Acquisition [Line Items]

% Sold

100.00%

100.00%

Sales Price

$ 267,500,000

$ 267,500,000

Gain (Loss) on Sale

9,500,000

Proceeds from sale of real estate held-for-investment, gross

254,500,000

Note receivable

$ 13,000,000

13,000,000

Term of note receivable

10 years

Deferred gain on sale of property

$ 13,000,000

13,000,000

Income (loss)

$ (1,900,000)

14,500,000

12,100,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations | Houston Properties

Business Acquisition [Line Items]

% Sold

100.00%

100.00%

Sales Price

$ 272,000,000

$ 272,000,000

Gain (Loss) on Sale

$ 63,700,000

Income (loss)

$ (14,900)

11,100,000

12,900,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations | SanTan Corporate Center

Business Acquisition [Line Items]

% Sold

100.00%

Sales Price

$ 58,500,000

Gain (Loss) on Sale

$ 9,800,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations | Sterling Commerce

Business Acquisition [Line Items]

% Sold

100.00%

Sales Price

$ 51,000,000

Gain (Loss) on Sale

$ 12,500,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations | 9127 South Jamaica Street

Business Acquisition [Line Items]

% Sold

100.00%

Sales Price

$ 19,500,000

Gain (Loss) on Sale

$ 0

Disposal Group, Disposed of by Sale, Not Discontinued Operations | 80 Park Plaza

Business Acquisition [Line Items]

% Sold

100.00%

Sales Price

$ 174,500,000

Gain (Loss) on Sale

$ 21,600,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations | 9189, 9191 & 9193 South Jamaica Street

Business Acquisition [Line Items]

% Sold

100.00%

Sales Price

$ 122,000,000

Gain (Loss) on Sale

$ 27,200,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations | 800 North Fredrick

Business Acquisition [Line Items]

% Sold

100.00%

Sales Price

$ 48,000,000

Gain (Loss) on Sale

$ 2,100,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations | 100 East Pratt

Business Acquisition [Line Items]

% Sold

100.00%

Sales Price

$ 187,000,000

Gain (Loss) on Sale

$ (300,000)

Disposal Group, Disposed of by Sale, Not Discontinued Operations | 1881 Campus Commons

Business Acquisition [Line Items]

% Sold

100.00%

Sales Price

$ 65,000,000

Gain (Loss) on Sale

$ 500,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations | Market Square Joint Venture

Business Acquisition [Line Items]

% Sold

49.00%

Sales Price

$ 291,600,000

Gain (Loss) on Sale

$ 3,100,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations | 11 Property Sale

Business Acquisition [Line Items]

% Sold

100.00%

Sales Price

$ 433,300,000

Gain (Loss) on Sale

$ 20,200,000

$ 73,200,000

Number of properties | property

11

Income from discontinued operations

$ 6,500,000

$ 3,000,000

Corporate Joint Venture

Business Acquisition [Line Items]

Ownership percentage

51.00%

Proceeds from sale of real estate

$ 120,000,000

Fair market value of property

$ 595,000,000

Corporate Joint Venture | Blackstone Property Partners

Business Acquisition [Line Items]

% Sold

49.00%

Mortgage note transferred to joint venture

$ 325,000,000

$ 325,000,000

325,000,000

$ 325,000,000

Bonds Payable | $300 Million Bridge Loan

Business Acquisition [Line Items]

Bridge loan

$ 300,000,000

Bonds Payable | $300 Million Bridge Loan

Business Acquisition [Line Items]

Repayments of debt

$ 119,000,000

1800 M Street Joint Venture | Corporate Joint Venture

Business Acquisition [Line Items]

Ownership percentage

55.00%

1800 M Street Joint Venture | Corporate Joint Venture

Business Acquisition [Line Items]

Ownership percentage

55.00%

1800 M Street Joint Venture | Corporate Joint Venture | Allianz

Business Acquisition [Line Items]

Ownership percentage

45.00%

San Francisco Joint Ventures | Corporate Joint Venture | Allianz

Business Acquisition [Line Items]

% Sold

22.50%

Proceeds from sale of interest in joint venture

$ 234,000,000

San Francisco Joint Ventures | Corporate Joint Venture | Subsequent Event

Business Acquisition [Line Items]

Proceeds from sale of interest in joint venture

$ 235,300,000

Ownership percentage

55.00%

San Francisco Joint Ventures | Corporate Joint Venture | Subsequent Event | Allianz

Business Acquisition [Line Items]

Additional ownership percentage acquired

22.50%

Unconsolidated Joint Ventures52

Unconsolidated Joint Ventures (Details) - USD ($) $ in Thousands	Feb. 01, 2018	Dec. 31, 2017	Oct. 11, 2017	Jul. 06, 2017	Dec. 31, 2016	Oct. 28, 2015
Corporate Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership percentage						51.00%
Carrying Value of Investment		$ 943,242			$ 127,346
Corporate Joint Venture | Market Square Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership percentage		51.00%				100.00%
Carrying Value of Investment		$ 128,411			127,346
Corporate Joint Venture | University Circle Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership percentage		77.50%
Carrying Value of Investment		$ 173,798			0
Corporate Joint Venture | 333 Market Street Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership percentage		77.50%
Carrying Value of Investment		$ 288,236			0
Corporate Joint Venture | 114 Fifth Avenue
Schedule of Equity Method Investments [Line Items]
Ownership percentage		49.50%		49.50%
Carrying Value of Investment		$ 110,311			0
Corporate Joint Venture | 1800 M Street Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership percentage		55.00%
Carrying Value of Investment		$ 242,486			$ 0
Allianz | Corporate Joint Venture | 114 Fifth Avenue
Schedule of Equity Method Investments [Line Items]
Ownership percentage				49.50%
Corporate Joint Venture | 114 Fifth Avenue
Schedule of Equity Method Investments [Line Items]
Ownership percentage				49.50%
Corporate Joint Venture | 1800 M Street Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership percentage			55.00%
Corporate Joint Venture | Allianz | 1800 M Street Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership percentage			45.00%
Subsequent Event | Corporate Joint Venture | San Francisco Joint Ventures
Schedule of Equity Method Investments [Line Items]
Ownership percentage	55.00%
Subsequent Event | Corporate Joint Venture | Allianz | San Francisco Joint Ventures
Schedule of Equity Method Investments [Line Items]
Additional ownership percentage acquired	22.50%

Unconsolidated Joint Ventures53

Unconsolidated Joint Ventures (Narrative) (Details) - Corporate Joint Venture - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Oct. 31, 2015	Oct. 28, 2015
Blackstone Property Partners
Related Party Transaction [Line Items]
Mortgage note transferred to joint venture	$ 325,000,000	$ 325,000,000			$ 325,000,000
Stated interest rate	5.07%	5.07%
Guaranty liability	$ 11,200,000	$ 16,100,000		$ 25,000,000
Other Property Income
Related Party Transaction [Line Items]
Reimbursement of property operating costs	2,000,000	500,000	$ 0
Prepaid Expenses and Other Assets
Related Party Transaction [Line Items]
Property management fees due to Columbia Property Trust	$ 400,000	$ 100,000

Unconsolidated Joint Ventures54

Unconsolidated Joint Ventures (Condensed Balance Sheet Information) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Total assets	$ 2,054,230	$ 587,344
Total debt	324,708	324,656
Total equity	1,443,406	242,802
Corporate Joint Venture | Market Square Joint Venture
Schedule of Equity Method Investments [Line Items]
Total assets	590,115	587,344
Total debt	324,708	324,656
Total equity	244,506	242,802
Corporate Joint Venture | University Circle Joint Venture
Schedule of Equity Method Investments [Line Items]
Total assets	227,368	0
Total debt	0	0
Total equity	221,154	0
Corporate Joint Venture | 333 Market Street Joint Venture
Schedule of Equity Method Investments [Line Items]
Total assets	385,297	0
Total debt	0	0
Total equity	368,994	0
Corporate Joint Venture | 114 Fifth Avenue
Schedule of Equity Method Investments [Line Items]
Total assets	392,486	0
Total debt	0	0
Total equity	170,525	0
Corporate Joint Venture | 1800 M Street Joint Venture
Schedule of Equity Method Investments [Line Items]
Total assets	458,964	0
Total debt	0	0
Total equity	438,227	$ 0
Corporate Joint Venture | University Circle, 333 Market Street Joint Venture,114 Fifth Avenue Joint Venture and 1800 M Street Joint Venture
Schedule of Equity Method Investments [Line Items]
Difference between carrying amount and underlying equity	$ 32,000

Unconsolidated Joint Ventures55

Unconsolidated Joint Ventures (Condensed Income Statement Information) (Details) - Corporate Joint Venture - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Total Revenues	$ 102,244	$ 41,230	$ 7,962
Net Income (Loss)	(2,684)	(14,825)	(2,239)
Columbia Property Trust's Share of Net Income (Loss)	2,651	(7,561)	(1,142)
Market Square Joint Venture
Schedule of Equity Method Investments [Line Items]
Total Revenues	41,749	41,230	7,962
Net Income (Loss)	(15,192)	(14,825)	(2,239)
Columbia Property Trust's Share of Net Income (Loss)	(7,747)	(7,561)	(1,142)
University Circle Joint Venture
Schedule of Equity Method Investments [Line Items]
Total Revenues	19,386	0	0
Net Income (Loss)	9,826	0	0
Columbia Property Trust's Share of Net Income (Loss)	7,561	0	0
333 Market Street Joint Venture
Schedule of Equity Method Investments [Line Items]
Total Revenues	12,971	0	0
Net Income (Loss)	6,948	0	0
Columbia Property Trust's Share of Net Income (Loss)	5,331	0	0
114 Fifth Avenue
Schedule of Equity Method Investments [Line Items]
Total Revenues	20,133	0	0
Net Income (Loss)	(4,885)	0	0
Columbia Property Trust's Share of Net Income (Loss)	(2,820)	0	0
1800 M Street Joint Venture
Schedule of Equity Method Investments [Line Items]
Total Revenues	8,005	0	0
Net Income (Loss)	619	0	0
Columbia Property Trust's Share of Net Income (Loss)	$ 326	$ 0	$ 0

Unconsolidated Joint Ventures56

Unconsolidated Joint Ventures (Property and Asset Management Fees) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Asset and property management fee income	$ 3,782	$ 2,122	$ 605
Corporate Joint Venture
Schedule of Equity Method Investments [Line Items]
Asset and property management fee income	3,782	2,122	213
Corporate Joint Venture | Market Square Joint Venture
Schedule of Equity Method Investments [Line Items]
Asset and property management fee income	1,998	2,122	213
Corporate Joint Venture | University Circle Joint Venture
Schedule of Equity Method Investments [Line Items]
Asset and property management fee income	1,000	0	0
Corporate Joint Venture | 333 Market Street Joint Venture
Schedule of Equity Method Investments [Line Items]
Asset and property management fee income	367	0	0
Corporate Joint Venture | 1800 M Street Joint Venture
Schedule of Equity Method Investments [Line Items]
Asset and property management fee income	$ 417	$ 0	$ 0

Line of Credit and Notes Paya57

Line of Credit and Notes Payable (Schedule of Long-Term Debt (excluding Bonds Payable)) (Details) - USD ($)	Nov. 27, 2017	Jul. 25, 2017	Jul. 24, 2017	Jul. 30, 2015	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Loans payable					$ 971,185,000	$ 971,185,000	$ 721,466,000
Less: Deferred financing costs related to term loans, bridge loan, and mortgage notes payable					(2,991,000)	(2,991,000)	(3,136,000)
Total indebtedness					971,185,000	971,185,000	721,466,000
Interest expense						21,500,000	27,800,000	$ 54,000,000
Property operating costs						87,805,000	154,968,000	$ 188,078,000
Term Loans
Debt Instrument [Line Items]
Less: Deferred financing costs related to term loans, bridge loan, and mortgage notes payable					(2,991,000)	(2,991,000)	(3,136,000)
Term Loans | $300 Million Term Loan
Debt Instrument [Line Items]
Debt face amount					300,000,000	300,000,000
Loans payable				$ 300,000,000	300,000,000	300,000,000	300,000,000
Term Loans | $150 Million Term Loan
Debt Instrument [Line Items]
Debt face amount					150,000,000	150,000,000
Loans payable		$ 150,000,000			150,000,000	150,000,000	150,000,000
Effective interest rate		3.07%	3.52%
Bridge Loan | $300 Million Bridge Loan
Debt Instrument [Line Items]
Debt face amount					300,000,000	300,000,000
Loans payable	$ 300,000,000				300,000,000	300,000,000	0
Credit Facilities | Revolving Credit Facility
Debt Instrument [Line Items]
Loans payable					$ 152,000,000	$ 152,000,000	0
Mortgages | 263 Shuman Boulevard Building mortgage note
Debt Instrument [Line Items]
Stated interest rate					10.55%	10.55%
Loans payable					$ 49,000,000	$ 49,000,000	49,000,000
Interest expense					$ 2,600,000
Default interest rate					10.55%
Property operating costs					$ 900,000
Mortgages | One Glenlake Building mortgage note
Debt Instrument [Line Items]
Stated interest rate					5.80%	5.80%
Loans payable					$ 23,176,000	$ 23,176,000	26,315,000
Mortgages | 650 California Street Building mortgage note
Debt Instrument [Line Items]
Stated interest rate					3.60%	3.60%
Loans payable					$ 0	$ 0	126,287,000
Mortgages | 221 Main Building mortgage note
Debt Instrument [Line Items]
Stated interest rate					3.95%	3.95%
Loans payable					$ 0	$ 0	$ 73,000,000
London Interbank Offered Rate (LIBOR) | Term Loans | $300 Million Term Loan
Debt Instrument [Line Items]
Variable rate margin						1.10%
London Interbank Offered Rate (LIBOR) | Term Loans | $150 Million Term Loan
Debt Instrument [Line Items]
Variable rate margin						1.10%
London Interbank Offered Rate (LIBOR) | Term Loans | Minimum | $300 Million Term Loan
Debt Instrument [Line Items]
Variable rate margin				0.90%
London Interbank Offered Rate (LIBOR) | Term Loans | Minimum | $150 Million Term Loan
Debt Instrument [Line Items]
Variable rate margin		0.90%	1.40%
London Interbank Offered Rate (LIBOR) | Term Loans | Maximum | $300 Million Term Loan
Debt Instrument [Line Items]
Variable rate margin				1.75%
London Interbank Offered Rate (LIBOR) | Term Loans | Maximum | $150 Million Term Loan
Debt Instrument [Line Items]
Variable rate margin		1.75%	2.35%
London Interbank Offered Rate (LIBOR) | Bridge Loan | $300 Million Bridge Loan
Debt Instrument [Line Items]
Variable rate margin						1.10%
London Interbank Offered Rate (LIBOR) | Bridge Loan | Minimum | $300 Million Bridge Loan
Debt Instrument [Line Items]
Variable rate margin	0.90%
London Interbank Offered Rate (LIBOR) | Bridge Loan | Maximum | $300 Million Bridge Loan
Debt Instrument [Line Items]
Variable rate margin	1.75%
London Interbank Offered Rate (LIBOR) | Credit Facilities | Revolving Credit Facility
Debt Instrument [Line Items]
Variable rate margin						1.00%
London Interbank Offered Rate (LIBOR) | Credit Facilities | Minimum | Revolving Credit Facility
Debt Instrument [Line Items]
Variable rate margin				0.875%
London Interbank Offered Rate (LIBOR) | Credit Facilities | Maximum | Revolving Credit Facility
Debt Instrument [Line Items]
Variable rate margin				1.55%
Base Rate | Term Loans | Minimum | $300 Million Term Loan
Debt Instrument [Line Items]
Variable rate margin				0.00%
Base Rate | Term Loans | Maximum | $300 Million Term Loan
Debt Instrument [Line Items]
Variable rate margin				0.75%
Base Rate | Bridge Loan | Minimum | $300 Million Bridge Loan
Debt Instrument [Line Items]
Variable rate margin	0.00%
Base Rate | Bridge Loan | Maximum | $300 Million Bridge Loan
Debt Instrument [Line Items]
Variable rate margin	0.75%
Base Rate | Credit Facilities | Minimum | Revolving Credit Facility
Debt Instrument [Line Items]
Variable rate margin				0.00%
Base Rate | Credit Facilities | Maximum | Revolving Credit Facility
Debt Instrument [Line Items]
Variable rate margin				0.55%
Interest Rate Swap
Debt Instrument [Line Items]
Notional amount					$ 150,000,000	$ 150,000,000

Line of Credit and Notes Paya58

Line of Credit and Notes Payable (Narrative) (Details)

Nov. 27, 2017USD ($)extension

Aug. 17, 2017USD ($)

Jul. 25, 2017USD ($)

Jul. 24, 2017

Mar. 10, 2017USD ($)

Oct. 03, 2016USD ($)

Jun. 30, 2016USD ($)

Apr. 01, 2016USD ($)

Jul. 30, 2015USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Debt Instrument [Line Items]

Loans payable

$ 971,185,000

$ 721,466,000

Carrying value of the line of credit, term loan and notes payable

$ 974,200,000

$ 724,600,000

Weighted-average interest rate

3.16%

3.09%

Interest payments

$ 21,500,000

$ 27,800,000

$ 54,000,000

Interest capitalized

700,000

300,000

600,000

Loss on early extinguishment of debt

325,000

18,997,000

$ 3,149,000

Fair Value, Inputs, Level 2

Debt Instrument [Line Items]

Fair value of line of credit and notes payable

$ 975,300,000

728,500,000

Letter of Credit | Maximum

Debt Instrument [Line Items]

Restrictive covenant ratio of secured debt to total asset

40.00%

Restrictive covenant ratio of debt to total asset

60.00%

Bridge Loan | $300 Million Bridge Loan

Debt Instrument [Line Items]

Line of credit facility, maximum borrowing capacity

$ 300,000,000

Debt term

1 year

Loans payable

$ 300,000,000

$ 300,000,000

0

Number of possible extensions | extension

1

Term of extension

6 months

Bridge Loan | $300 Million Bridge Loan | London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Variable rate margin

1.10%

Bridge Loan | $300 Million Bridge Loan | London Interbank Offered Rate (LIBOR) | Minimum

Debt Instrument [Line Items]

Variable rate margin

0.90%

Bridge Loan | $300 Million Bridge Loan | London Interbank Offered Rate (LIBOR) | Maximum

Debt Instrument [Line Items]

Variable rate margin

1.75%

Bridge Loan | $300 Million Bridge Loan | Base Rate | Minimum

Debt Instrument [Line Items]

Variable rate margin

0.00%

Bridge Loan | $300 Million Bridge Loan | Base Rate | Maximum

Debt Instrument [Line Items]

Variable rate margin

0.75%

Term Loans | $300 Million Term Loan

Debt Instrument [Line Items]

Loans payable

$ 300,000,000

$ 300,000,000

300,000,000

Term Loans | $300 Million Term Loan | London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Variable rate margin

1.10%

Term Loans | $300 Million Term Loan | London Interbank Offered Rate (LIBOR) | Minimum

Debt Instrument [Line Items]

Variable rate margin

0.90%

Term Loans | $300 Million Term Loan | London Interbank Offered Rate (LIBOR) | Maximum

Debt Instrument [Line Items]

Variable rate margin

1.75%

Term Loans | $300 Million Term Loan | Base Rate | Minimum

Debt Instrument [Line Items]

Variable rate margin

0.00%

Term Loans | $300 Million Term Loan | Base Rate | Maximum

Debt Instrument [Line Items]

Variable rate margin

0.75%

Term Loans | $150 Million Term Loan

Debt Instrument [Line Items]

Loans payable

$ 150,000,000

$ 150,000,000

150,000,000

Effective interest rate

3.07%

3.52%

Term Loans | $150 Million Term Loan | London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Variable rate margin

1.10%

Term Loans | $150 Million Term Loan | London Interbank Offered Rate (LIBOR) | Minimum

Debt Instrument [Line Items]

Variable rate margin

0.90%

1.40%

Term Loans | $150 Million Term Loan | London Interbank Offered Rate (LIBOR) | Maximum

Debt Instrument [Line Items]

Variable rate margin

1.75%

2.35%

Credit Facilities | Revolving Credit Facility

Debt Instrument [Line Items]

Loans payable

$ 152,000,000

0

Repayments of debt

$ 99,000,000

Credit Facilities | Revolving Credit Facility | London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Variable rate margin

1.00%

Credit Facilities | Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Minimum

Debt Instrument [Line Items]

Variable rate margin

0.875%

Credit Facilities | Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Maximum

Debt Instrument [Line Items]

Variable rate margin

1.55%

Credit Facilities | Revolving Credit Facility | Base Rate | Minimum

Debt Instrument [Line Items]

Variable rate margin

0.00%

Credit Facilities | Revolving Credit Facility | Base Rate | Maximum

Debt Instrument [Line Items]

Variable rate margin

0.55%

Unsecured Debt

Debt Instrument [Line Items]

Fixed charge coverage ratio

1.50

Unencumbered adjusted net operating income to unsecured interest expense ratio, minimum

1.75

Unencumbered asset value to unsecured debt ratio, minimum

1.66

Unsecured Debt | $300 Million Bridge Loan

Debt Instrument [Line Items]

Repayments of debt

$ 119,000,000

Loss on early extinguishment of debt

$ 82,000

Mortgages | SanTan Corporate Center mortgage notes

Debt Instrument [Line Items]

Repayments of debt

$ 39,000,000

Write off of related unamortized financing costs

$ 10,000

Mortgages | 650 California Street Building mortgage note

Debt Instrument [Line Items]

Loans payable

$ 0

126,287,000

Repayments of debt

$ 124,800,000

Loss on early extinguishment of debt

$ 300,000

Mortgages | 221 Main Building mortgage note

Debt Instrument [Line Items]

Loans payable

$ 0

$ 73,000,000

Repayments of debt

$ 73,000,000

Loss on early extinguishment of debt

$ 45,000

Line of Credit and Notes Paya59

Line of Credit and Notes Payable (Maturities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
2,018	$ 323,176
2,019	152,000
2,020	300,000
2,021	0
2,022	150,000
Thereafter	0
Total	925,176
Debt Instrument [Line Items]
Loans payable	971,185	$ 721,466
Mortgages | 263 Shuman Boulevard Building mortgage note
Debt Instrument [Line Items]
Loans payable	$ 49,000	$ 49,000

Bonds Payable (Details)

Bonds Payable (Details)	Aug. 12, 2016USD ($)	Aug. 31, 2016USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Debt Instrument [Line Items]
Proceeds from issuance of bonds payable				$ 0	$ 348,691,000	$ 349,507,000
Initial issuance discount of bonds payable				1,484,000	1,664,000
Bonds payable, net				698,500,000	698,300,000
Bonds Payable | 2026 Bonds Payable
Debt Instrument [Line Items]
Debt face amount	$ 350,000,000	$ 350,000,000
Debt term	10 years	10 years
Stated interest rate	3.65%	3.65%
Discount rate of face value of issued debt instrument (percent)	99.626%	99.626%
Proceeds from issuance of bonds payable	$ 346,400,000
Initial issuance discount of bonds payable	1,300,000
Bonds Payable | 2018 Bonds Payable
Debt Instrument [Line Items]
Debt face amount	$ 250,000,000
Stated interest rate	5.875%
Maturity period of debt instrument	7 years
Bonds Payable | 2025 Bonds Payable
Debt Instrument [Line Items]
Debt face amount			$ 350,000,000
Debt term			10 years
Stated interest rate			4.15%
Discount rate of face value of issued debt instrument (percent)			99.859%
Proceeds from issuance of bonds payable			$ 347,200,000
Initial issuance discount of bonds payable			$ 500,000
Bonds Payable | 2026 and 2025 Bonds Payable
Debt Instrument [Line Items]
Interest payments				$ 27,400,000
Restrictive covenant ratio of debt to total asset				60.00%
Restrictive covenant of consolidated income to annual debt service charges, term				12 months
Bonds Payable | 2025 and 2018 Bonds Payable
Debt Instrument [Line Items]
Interest payments					28,000,000
Fair Value, Inputs, Level 2 | Bonds Payable | 2026 and 2025 Bonds Payable
Debt Instrument [Line Items]
Estimated fair value of debt instrument				$ 702,800,000	$ 703,100,000
Maximum | Bonds Payable | 2026 and 2025 Bonds Payable
Debt Instrument [Line Items]
Restrictive covenant ratio of secured debt to total asset				40.00%
Minimum | Bonds Payable | 2026 and 2025 Bonds Payable
Debt Instrument [Line Items]
Restrictive covenant of consolidated income to annual debt service charges				1.5
Ratio of unencumbered asset value to total unsecured debt				150.00%

Commitments and Contingencies61

Commitments and Contingencies (Lease Obligations) (Details)	12 Months Ended
	Dec. 31, 2017USD ($)propertyTenant	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Oct. 31, 2015USD ($)
Loss Contingencies [Line Items]
Number of tenants that have exercised the option to expand property | Tenant	0
Number of properties subject to ground leases | property	3
Rent expenses incurred	$ 2,600,000	$ 2,600,000	$ 2,600,000
Obligations Under Operating Leases
2,018	3,282,000
2,019	3,360,000
2,020	3,382,000
2,021	3,405,000
2,022	3,587,000
Thereafter	192,352,000
Total	209,368,000
Obligations Under Capital Leases
2,018	7,200,000
2,019	7,200,000
2,020	7,200,000
2,021	127,200,000
2,022	0
Thereafter	0
Total payments with interest	148,800,000
Amounts representing interest	(28,800,000)
Total	120,000,000
Corporate Joint Venture | Blackstone Property Partners
Loss Contingencies [Line Items]
Guaranty liability	$ 11,200,000	$ 16,100,000		$ 25,000,000

Equity (Narrative) (Details)

Equity (Narrative) (Details) - USD ($)	Jan. 01, 2018	Jan. 20, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 04, 2017	Dec. 31, 2016	May 31, 2017	Sep. 04, 2015
Class of Stock [Line Items]
Common stock, par value (in dollars per share)			$ 0.01	$ 0.01			$ 0.01
Performance period			3 years	1 year
Long Term Incentive Plan
Class of Stock [Line Items]
Shares authorized and reserved under the LTIP								4,800,000
Unrecognized compensation costs related to unvested awards			$ 8,100,000	$ 3,200,000			$ 3,200,000
RSUs
Class of Stock [Line Items]
Granted (shares)			331,000
RSUs | Long Term Incentive Plan
Class of Stock [Line Items]
Granted (shares)			193,219
Performance period			3 years
Stock Options | Director Stock Option Plan
Class of Stock [Line Items]
Shares authorized and reserved under the LTIP			25,000
Number of shares granted			0	0	0
Minimum
Class of Stock [Line Items]
Unrecognized compensation costs recognition period			1 year
Minimum | RSUs | Long Term Incentive Plan
Class of Stock [Line Items]
Shareholder payout (percent)			50.00%
Maximum
Class of Stock [Line Items]
Unrecognized compensation costs recognition period			4 years
Maximum | RSUs | Long Term Incentive Plan
Class of Stock [Line Items]
Shareholder payout (percent)			150.00%
12 months after grant date | RSUs | Long Term Incentive Plan
Class of Stock [Line Items]
Award vesting rights (percent)			25.00%
48 months after grant date | RSUs | Long Term Incentive Plan
Class of Stock [Line Items]
Award vesting rights (percent)			75.00%
Subsequent Event | RSUs | Long Term Incentive Plan
Class of Stock [Line Items]
Granted (shares)	176,702
Performance period	3 years
Subsequent Event | Time-based Stock Awards | Long Term Incentive Plan
Class of Stock [Line Items]
Granted (shares)	128,486
Stock units exercisable period after the date of grant	4 years
Subsequent Event | 12 months after grant date | RSUs | Long Term Incentive Plan
Class of Stock [Line Items]
Award vesting rights (percent)	25.00%
Subsequent Event | 48 months after grant date | RSUs | Long Term Incentive Plan
Class of Stock [Line Items]
Award vesting rights (percent)	75.00%
Common Stock | Long Term Incentive Plan
Class of Stock [Line Items]
Granted (shares)		193,535	139,825
Shares withheld to settle related tax liability		17,938
Stock units exercisable period after the date of grant			4 years
Common Stock | 2015 Stock Repurchase Program
Class of Stock [Line Items]
Stock repurchase program, authorized amount									$ 200,000,000
Common stock, par value (in dollars per share)									$ 0.01
Number of shares repurchased (in shares)						5,600,000
Shares repurchased, average cost per share (in dollars per share)						$ 21.85
Value of stock repurchased						$ 121,400,000
Common Stock | 2017 Stock Repurchase Program
Class of Stock [Line Items]
Stock repurchase program, authorized amount						$ 200,000,000
Common stock, par value (in dollars per share)						$ 0.01
Common Stock | Stock Repurchase Program
Class of Stock [Line Items]
Number of shares repurchased (in shares)							2,700,000
Shares repurchased, average cost per share (in dollars per share)							$ 21.46
Value of stock repurchased							$ 57,600,000
Stock repurchase program, amount available for repurchase			$ 194,800,000
Common Stock | Grant date | Long Term Incentive Plan
Class of Stock [Line Items]
Award vesting rights (percent)		25.00%
Common Stock | 12 months after grant date | Long Term Incentive Plan
Class of Stock [Line Items]
Award vesting rights (percent)		25.00%	25.00%
Common Stock | 24 months after grant date | Long Term Incentive Plan
Class of Stock [Line Items]
Award vesting rights (percent)		25.00%	25.00%
Common Stock | 36 months after grant date | Long Term Incentive Plan
Class of Stock [Line Items]
Award vesting rights (percent)		25.00%	25.00%
2017 Grant 1 | RSUs | Long Term Incentive Plan
Class of Stock [Line Items]
Granted (shares)			45,076
Performance period			1 year
2017 Grant 2 | RSUs | Long Term Incentive Plan
Class of Stock [Line Items]
Granted (shares)			92,585
Performance period			2 years

Equity (Unvested Activity Rollf

Equity (Unvested Activity Rollforward) (Details) - Long Term Incentive Plan - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested shares, beginning balance (shares)	256	151	104
Granted (shares)	333	247	123
Vested (shares)	(193)	(138)	(74)
Forfeited (shares)	(7)	(4)	(2)
Unvested shares, ending balance (shares)	389	256	151
Weighted-Average Grant-Date Fair Value [Abstract]
Unvested shares, beginning balance (in dollars per share)	$ 22.62	$ 24.59	$ 24.82
Granted (in dollars per share)	21.59	21.79	24.40
Vested (in dollars per share)	22.42	23.32	24.60
Forfeited (in dollars per share)	21.81	21.90	24.56
Unvested shares, ending balance (in dollars per share)	$ 21.85	$ 22.62	$ 24.59
Shares expected to ultimately vest	370
Expected forfeiture rate	5.00%

Equity (Performance-Based RSUs)

Equity (Performance-Based RSUs) (Details) - RSUs shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested shares, beginning balance (shares)	0
Granted (shares)	331
Vested (shares)	0
Forfeited (shares)	(2)
Unvested shares, ending balance (shares)	329
Weighted-Average Grant-Date Fair Value [Abstract]
Unvested shares, beginning balance (in dollars per share) | $ / shares	$ 0
Granted (in dollars per share) | $ / shares	18.78
Vested (in dollars per share) | $ / shares	0
Forfeited (in dollars per share) | $ / shares	19.01
Unvested shares, ending balance (in dollars per share) | $ / shares	$ 18.78
Shares expected to ultimately vest	303
Expected forfeiture rate	8.00%

Equity (Summary of Shares Grant

Equity (Summary of Shares Granted to Independent Director) (Details) - Long Term Incentive Plan - $ / shares

Nov. 27, 2017

May 02, 2017

Jan. 03, 2017

Oct. 03, 2016

Jul. 01, 2016

Apr. 01, 2016

Jan. 04, 2016

Oct. 01, 2015

Jul. 01, 2015

Apr. 01, 2015

Jan. 02, 2015

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares

333,000

247,000

123,000

Weighted-Average Grant-Date Fair Value (in dollars per share)

$ 21.59

$ 21.79

$ 24.40

January 3, 2017 | Director

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares

8,279

Weighted-Average Grant-Date Fair Value (in dollars per share)

$ 21.58

May 2, 2017 | Director

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares

33,581

Weighted-Average Grant-Date Fair Value (in dollars per share)

$ 22.57

November 27, 2017 | Director

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares

1,596

Weighted-Average Grant-Date Fair Value (in dollars per share)

$ 23.07

January 4, 2016 | Director

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares

7,439

Weighted-Average Grant-Date Fair Value (in dollars per share)

$ 23

April 1, 2016 | Director

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares

8,120

Weighted-Average Grant-Date Fair Value (in dollars per share)

$ 21.89

July 1, 2016 | Director

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares

8,158

Weighted-Average Grant-Date Fair Value (in dollars per share)

$ 21.52

October 3, 2016 | Director

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares

7,727

Weighted-Average Grant-Date Fair Value (in dollars per share)

$ 22.19

January 2, 2015 | Director

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares

5,850

Weighted-Average Grant-Date Fair Value (in dollars per share)

$ 25.75

April 1, 2015 | Director

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares

4,995

Weighted-Average Grant-Date Fair Value (in dollars per share)

$ 27.16

July 1, 2015 | Director

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares

4,144

Weighted-Average Grant-Date Fair Value (in dollars per share)

$ 24.84

October 1, 2015 | Director

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares

4,571

Weighted-Average Grant-Date Fair Value (in dollars per share)

$ 23.40

Equity (Stock-Based Compensatio

Equity (Stock-Based Compensation Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 7,580	$ 4,558	$ 3,548
Future employee awards	2,509	1,006	1,353
Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	4,098	2,856	1,699
Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 973	$ 696	$ 496

Equity (Summary of Stock Option

Equity (Summary of Stock Option Under the Director Plan) (Details) - Director Stock Option Plan - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number
Outstanding, beginning period (shares)	1,375	1,875	3,875
Granted (shares)	0	0	0
Expired (shares)	(1,375)	(500)	(2,000)
Outstanding, period end (shares)	0	1,375	1,875
Exercise Price
Outstanding exercise price, beginning period (in dollars per share)	$ 48	$ 48	$ 48
Outstanding exercise price, period end (in dollars per share)	$ 0	$ 48	$ 48
Exercisable
Outstanding shares exercisable, beginning period (shares)	1,375	1,875	3,875
Outstanding shares exercisable, period end (shares)	0	1,375	1,875

Operating Leases (Details)

Operating Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Operating Leases, Future Minimum Payments Receivable [Abstract]
2,018	$ 231,641
2,019	247,774
2,020	243,053
2,021	207,919
2,022	192,322
Thereafter	1,440,917
Total	2,563,626
Lease inducement obligations	$ 66,300
Lease term	30 years
Lease revenue | Customer concentration risk
Operating Leased Assets [Line Items]
Concentration risk percentage	6.00%
Number of properties | New York | Geographic concentration risk
Operating Leased Assets [Line Items]
Concentration risk percentage	38.00%
Number of properties | San Francisco | Geographic concentration risk
Operating Leased Assets [Line Items]
Concentration risk percentage	28.00%
Number of properties | Washington, D.C. | Geographic concentration risk
Operating Leased Assets [Line Items]
Concentration risk percentage	14.00%
Business services industry | Lease revenue | Customer concentration risk
Operating Leased Assets [Line Items]
Concentration risk percentage	23.00%
Banking industry | Lease revenue | Customer concentration risk
Operating Leased Assets [Line Items]
Concentration risk percentage	11.00%
Engineering and management services | Lease revenue | Customer concentration risk
Operating Leased Assets [Line Items]
Concentration risk percentage	8.00%

Supplemental Disclosure of No69

Supplemental Disclosure of Noncash Investing and Financing Activities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Elements [Abstract]
Investment in real estate funded with other assets	$ 311	$ 1,442	$ 27,000
Deposits applied to sales of real estate	10,000	0	0
Other assets assumed upon acquisition	1,014	0	7,785
Other liabilities assumed upon acquisition	268	0	4,765
Real estate assets transferred to unconsolidated joint venture	558,122	0	531,696
Mortgage note transferred to unconsolidated joint venture	0	0	325,000
Other assets transferred to unconsolidated joint venture	43,700	0	37,987
Other liabilities transferred to unconsolidated joint venture	21,347	0	20,595
Discount on issuance of bonds payable	0	1,309	494
Amortization of discounts (premiums) on debt	180	267	(18)
Market value adjustment to interest rate swaps that qualify for hedge accounting treatment	1,786	1,553	(1,570)
Accrued capital expenditures and deferred lease costs	25,069	15,042	19,324
Accrued dividends payable	23,961	36,727	37,354
Common stock issued to employees and directors, and amortized (net of income tax witholdings)	$ 5,764	$ 3,388	$ 3,548

Income Taxes (Schedule of Incom

Income Taxes (Schedule of Income Tax Basis Net Income) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
GAAP basis financial statement net income attributable to the common stockholders of Columbia Property Trust, Inc.	$ (1,348)	$ 101,534	$ 1,133	$ 74,722	$ 27,400	$ 36,898	$ 13,286	$ 6,697	$ 176,041	$ 84,281	$ 44,619
Increase (Decrease) in Net Income Resulting From:
Depreciation and amortization expense for financial reporting purposes in excess of amounts for income tax purposes									33,918	34,569	81,559
Rental income accrued for financial reporting purposes in excess of amounts for income tax purposes									(38,426)	(26,900)	(13,409)
Net amortization of above-/below-market lease intangibles for financial reporting purposes less than amounts for income tax purposes									(6,091)	(9,013)	(6,626)
Gain on interest rate swaps that do not qualify for hedge accounting treatment for financial reporting purposes in excess of amounts for income tax purposes									0	0	(2,633)
Bad debt expense for financial reporting purposes less than amounts for income tax purposes									(31)	(261)	5
Income from unconsolidated joint ventures for financial reporting purchases in excess of amount for income tax purposes									13,902	0	0
Gains or losses on disposition of real property for financial reporting purposes that are more favorable than amounts for income tax purposes									(126,770)	(71,701)	(117,857)
Other expenses for financial reporting purposes in excess of amounts for income tax purposes									11,331	(2,707)	14,342
Income tax basis net income, prior to dividends-paid deduction									63,874	$ 8,268	$ 0
Tax basis carrying value of total assets	$ 4,600,000								$ 4,600,000

Income Taxes (Distributions) (D

Income Taxes (Distributions) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Ordinary income	58.50%	5.60%	0.00%
Capital gains	0.00%	0.00%	0.00%
Return of capital	41.50%	94.40%	100.00%
Total	100.00%	100.00%	100.00%

Income Taxes (Effective Tax Rat

Income Taxes (Effective Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Total income tax	$ (213)	$ 445	$ 378
Deferred tax asset	205
Deferred tax liabilities		22
Columbia TRS
Income Tax Contingency [Line Items]
Federal income tax	188	255	17
State income tax	38	21	25
Total income tax	$ 226	$ 276	$ 42

Earnings Per Share (Schedule of

Earnings Per Share (Schedule of Basic and Diluted EPS Computation) (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income	$ (1,348)	$ 101,534	$ 1,133	$ 74,722	$ 27,400	$ 36,898	$ 13,286	$ 6,697	$ 176,041	$ 84,281	$ 44,619
Distributions paid on unvested shares									(337)	(314)	(185)
Net income used to calculate basic and diluted earnings per share									$ 175,704	$ 83,967	$ 44,434
Weighted-average common shares – basic									120,795	123,130	124,757
Weighted-average common shares – diluted									121,159	123,228	124,847
Previously granted LTIP awards, unvested
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Plus Incremental Weighted-Average Shares From Time-Vested Conversions Less Assumed Share Repurchases									116	58	33
Future LTIP awards
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Plus Incremental Weighted-Average Shares From Time-Vested Conversions Less Assumed Share Repurchases									248	40	57

Quarterly Results (Unaudited)74

Quarterly Results (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 01, 2015	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues		$ 71,625	$ 60,362	$ 74,857	$ 82,156	$ 105,768	$ 113,266	$ 127,930	$ 126,579	$ 289,000	$ 473,543	$ 566,065
Net income		$ (1,348)	$ 101,534	$ 1,133	$ 74,722	$ 27,400	$ 36,898	$ 13,286	$ 6,697	$ 176,041	$ 84,281	$ 44,619
Net income per share - basic (in dollars per share)		$ (0.01)	$ 0.84	$ 0.01	$ 0.61	$ 0.22	$ 0.30	$ 0.11	$ 0.05	$ 1.45	$ 0.68	$ 0.36
Net income per share - diluted (in dollars per share)		(0.01)	0.84	0.01	0.61	0.22	0.30	0.11	0.05	$ 1.45	$ 0.68	$ 0.36
Dividends declared per share (in dollars per share)		$ 0.2	$ 0.2	$ 0.2	$ 0.20	$ 0.30	$ 0.30	$ 0.30	$ 0.30
Gain (loss) on the early extinguishment of debt			$ 102,400							$ (325)	$ (18,997)	$ (3,149)
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of real estate						$ 22,200
Disposal Group, Disposed of by Sale, Not Discontinued Operations | 11 Property Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of real estate	$ 20,200				$ 73,200
Disposal Group, Disposed of by Sale, Not Discontinued Operations | South Jamaica Street and 100 East Pratt Buildings
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of real estate							$ 50,400
Bonds Payable | 2018 Bonds Payable
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on the early extinguishment of debt							$ (18,900)
222 East 41st Street
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Early termination payment								$ 6,200

Segment Information (Operating

Segment Information (Operating Revenues By Geographic Reportable Segment) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jul. 06, 2017	Jul. 05, 2017	Oct. 28, 2015
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture									$ 345,955	$ 492,448	$ 569,520
Operating revenues	$ 71,625	$ 60,362	$ 74,857	$ 82,156	$ 105,768	$ 113,266	$ 127,930	$ 126,579	289,000	473,543	566,065
Asset and property management fee income									3,782	2,122	605
Operating Segments
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture									344,048	469,093	544,670
Operating Segments | New York
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture									123,280	117,235	97,643
Operating Segments | San Francisco
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture									105,550	109,995	112,696
Operating Segments | Atlanta
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture									37,803	36,742	35,715
Operating Segments | Washington, D.C.
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture									36,934	33,024	62,766
Operating Segments | Boston
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture									11,559	11,796	20,895
Operating Segments | Los Angeles
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture									7,462	7,443	7,588
Operating Segments | All other office markets
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture									21,460	152,858	207,367
Hotel
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture									1,328	22,958	24,583
Asset and property management fee income									3,782	2,122	605
Corporate
Segment Reporting Information [Line Items]
Operating revenues including unconsolidated joint venture									579	397	267
Joint Venture
Segment Reporting Information [Line Items]
Operating revenues									60,737	21,027	4,060
Asset and property management fee income									(3,782)	(2,122)	(605)
Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage														51.00%
Asset and property management fee income									$ 3,782	2,122	213
114 Fifth Avenue | Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage	49.50%								49.50%			49.50%
University Circle & 333 Market Street | Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage	77.50%								77.50%				100.00%
Market Square Joint Venture | Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage	51.00%								51.00%					100.00%
Asset and property management fee income									$ 1,998	2,122	213
1800 M Street Joint Venture | Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage	55.00%								55.00%
Asset and property management fee income									$ 417	$ 0	$ 0

Segment Information (Reconcilia

Segment Information (Reconciliation of Net Operating Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jul. 06, 2017	Jul. 05, 2017	Oct. 28, 2015
Segment Reporting Information [Line Items]
Net operating income including consolidated joint venture	$ 228,875	$ 306,101	$ 357,966
Operating Segments
Segment Reporting Information [Line Items]
Net operating income including consolidated joint venture	230,614	302,271	353,959
Operating Segments | New York
Segment Reporting Information [Line Items]
Net operating income including consolidated joint venture	73,893	70,038	54,692
Operating Segments | San Francisco
Segment Reporting Information [Line Items]
Net operating income including consolidated joint venture	76,163	80,529	83,826
Operating Segments | Atlanta
Segment Reporting Information [Line Items]
Net operating income including consolidated joint venture	33,603	32,939	31,912
Operating Segments | Washington, D.C.
Segment Reporting Information [Line Items]
Net operating income including consolidated joint venture	18,496	16,372	36,958
Operating Segments | Boston
Segment Reporting Information [Line Items]
Net operating income including consolidated joint venture	5,380	5,114	12,519
Operating Segments | Los Angeles
Segment Reporting Information [Line Items]
Net operating income including consolidated joint venture	4,529	4,523	4,853
Operating Segments | All other office markets
Segment Reporting Information [Line Items]
Net operating income including consolidated joint venture	18,550	92,756	129,199
Hotel
Segment Reporting Information [Line Items]
Net operating income including consolidated joint venture	(913)	3,988	4,593
Corporate
Segment Reporting Information [Line Items]
Net operating income including consolidated joint venture	$ (826)	$ (158)	$ (586)
Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage						51.00%
114 Fifth Avenue | Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage	49.50%			49.50%
University Circle & 333 Market Street | Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage	77.50%				100.00%
Market Square Joint Venture | Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage	51.00%					100.00%
1800 M Street Joint Venture | Corporate Joint Venture
Segment Reporting Information [Line Items]
Ownership percentage	55.00%

Segment Information (Reconcil77

Segment Information (Reconciliation of GAAP Net Income to NOI) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net income	$ (1,348)	$ 101,534	$ 1,133	$ 74,722	$ 27,400	$ 36,898	$ 13,286	$ 6,697	$ 176,041	$ 84,281	$ 44,619
Depreciation									80,394	108,543	131,490
Amortization									32,403	56,775	87,128
General and administrative – corporate									34,966	33,876	29,683
General and administrative – joint venture									1,454	0	0
Real estate acquisition costs									0	0	3,675
Settlement of interest rate swap									0	0	1,110
Loss on early extinguishment of debt		$ (102,400)							325	18,997	3,149
Income tax expense									(213)	445	378
Asset and property management fee income									(3,782)	(2,122)	(605)
Gain on sale of real estate assets									(175,518)	(72,325)	(23,860)
Net operating income									228,875	306,101	357,966
Segment Reconciling Items
Segment Reporting Information [Line Items]
Depreciation									80,394	108,543	131,490
Amortization									32,403	56,775	87,128
General and administrative – corporate									34,966	33,876	29,683
General and administrative – joint venture									1,454	0	0
Real estate acquisition costs									0	0	3,675
Net interest expense									58,187	67,538	85,265
Interest income from development authority bonds									(7,200)	(7,200)	(7,200)
Interest rate swap valuation adjustment									0	0	(2,634)
Interest expense associated with interest rate swap									0	0	2,642
Settlement of interest rate swap									0	0	1,102
Loss on early extinguishment of debt									325	18,997	3,149
Income tax expense									(213)	445	378
Asset and property management fee income									(3,782)	(2,122)	(605)
Adjustments included in loss from unconsolidated joint venture									31,818	17,293	3,134
Gain on sale of real estate assets									$ (175,518)	$ (72,325)	$ (23,860)

Financial Information for Par78

Financial Information for Parent Guarantor, Other Guarantor Subsidiaries, and Non-Guarantor Subsidiaries (Narratives) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Ownership percentage of wholly owned subsidiary	100.00%
Increase in cash flows from operating activities	$ 61,924	$ 193,091	$ 223,080
Increase (decrease) in cash flows from investing cash flows	(347,723)	525,613	(576,699)
Increase (decrease) in cash flows from financing activities	79,281	(535,264)	236,474
Columbia Property Trust (Parent) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Increase in cash flows from operating activities	3,966	53,980	15,743
Increase (decrease) in cash flows from investing cash flows	(8,671)	321,911	(4,615)
Increase (decrease) in cash flows from financing activities	(169,023)	(202,460)	(129,627)
Columbia Property Trust OP (the Issuer) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Increase in cash flows from operating activities	(46,268)	86,846	(50,601)
Increase (decrease) in cash flows from investing cash flows	(417,235)	550,111	(633,893)
Increase (decrease) in cash flows from financing activities	452,073	(635,417)	688,959
Non- Guarantors | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Increase in cash flows from operating activities	104,226	242,118	273,655
Increase (decrease) in cash flows from investing cash flows	(27,993)	543,982	(571,199)
Increase (decrease) in cash flows from financing activities	$ (97,593)	(777,631)	294,433
Intercompany Cash Transfers Between Parent and Subsidiaries Broken Out by Cash Flow Type | Restatement Adjustment | Columbia Property Trust (Parent) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Increase in cash flows from operating activities		53,100	15,700
Increase (decrease) in cash flows from investing cash flows		(281,800)	1,045,900
Increase (decrease) in cash flows from financing activities		228,700	(1,061,600)
Intercompany Cash Transfers Between Parent and Subsidiaries Broken Out by Cash Flow Type | Restatement Adjustment | Columbia Property Trust OP (the Issuer) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Increase in cash flows from operating activities		136,700
Increase (decrease) in cash flows from investing cash flows		568,500	(145,300)
Increase (decrease) in cash flows from financing activities		(705,200)	145,300
Intercompany Cash Transfers Between Parent and Subsidiaries Broken Out by Cash Flow Type | Restatement Adjustment | Non- Guarantors | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Increase (decrease) in cash flows from investing cash flows		603,700	(468,000)
Increase (decrease) in cash flows from financing activities		$ (603,700)	$ 468,000

Financial Information for Par79

Financial Information for Parent Guarantor, Other Guarantor Subsidiaries, and Non-Guarantor Subsidiaries (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Real Estate Assets, at Cost:
Land	$ 825,208	$ 751,351
Buildings and improvements, net	2,063,419	2,121,150
Intangible lease assets, net	199,260	193,311
Construction in progress	44,742	36,188
Real estate assets held for sale, net	0	412,506
Total real estate assets	3,132,629	3,514,506
Investment in unconsolidated joint ventures	943,242	127,346
Cash and cash equivalents	9,567	216,085	$ 32,645	$ 149,790
Investment in subsidiaries	0	0
Tenant receivables, net of allowance	2,128	7,163
Straight-line rent receivable	92,235	64,811
Prepaid expenses and other assets	27,683	24,275
Intangible lease origination costs, net	42,959	54,279
Deferred lease costs, net	141,096	125,799
Investment in development authority bonds	120,000	120,000
Other assets held for sale, net	0	45,529
Total assets	4,511,539	4,299,793
Liabilities:
Line of credit and notes payable, net	971,185	721,466
Bonds payable, net	693,756	692,972
Accounts payable, accrued expenses, and accrued capital expenditures	125,002	131,028
Dividends payable	23,961	36,727	37,354
Due to affiliates	0	0
Deferred income	18,481	19,694
Intangible lease liabilities, net	27,218	33,375
Obligations under capital leases	120,000	120,000
Liabilities held for sale, net	0	41,763
Total liabilities	1,979,603	1,797,025
Equity:
Total equity	2,531,936	2,502,768	2,614,194	2,733,478
Total liabilities and equity	4,511,539	4,299,793
Consolidating Adjustments
Real Estate Assets, at Cost:
Land	0	0
Buildings and improvements, net	0	0
Intangible lease assets, net	0	0
Construction in progress	0	0
Real estate assets held for sale, net		0
Total real estate assets	0	0
Investment in unconsolidated joint ventures	0	0
Cash and cash equivalents	0	0	0	0
Investment in subsidiaries	(3,425,171)	(3,830,674)
Tenant receivables, net of allowance	0	0
Straight-line rent receivable	0	0
Prepaid expenses and other assets	(645,654)	(570,687)
Intangible lease origination costs, net	0	0
Deferred lease costs, net	0	0
Investment in development authority bonds	0	0
Other assets held for sale, net		(52)
Total assets	(4,070,825)	(4,401,413)
Liabilities:
Line of credit and notes payable, net	(643,310)	(430,762)
Bonds payable, net	0	0
Accounts payable, accrued expenses, and accrued capital expenditures	(4)	0
Dividends payable	0	0
Due to affiliates	(2,340)	(1,592)
Deferred income	0	0
Intangible lease liabilities, net	0	0
Obligations under capital leases	0	0
Liabilities held for sale, net		(138,385)
Total liabilities	(645,654)	(570,739)
Equity:
Total equity	(3,425,171)	(3,830,674)
Total liabilities and equity	(4,070,825)	(4,401,413)
Columbia Property Trust (Parent) | Reportable Legal Entities
Real Estate Assets, at Cost:
Land	0	0
Buildings and improvements, net	0	0
Intangible lease assets, net	0	0
Construction in progress	0	0
Real estate assets held for sale, net		0
Total real estate assets	0	0
Investment in unconsolidated joint ventures	0	0
Cash and cash equivalents	692	174,420	989	119,488
Investment in subsidiaries	2,238,577	2,047,922
Tenant receivables, net of allowance	0	0
Straight-line rent receivable	0	0
Prepaid expenses and other assets	317,364	317,153
Intangible lease origination costs, net	0	0
Deferred lease costs, net	0	0
Investment in development authority bonds	0	0
Other assets held for sale, net		0
Total assets	2,556,633	2,539,495
Liabilities:
Line of credit and notes payable, net	0	0
Bonds payable, net	0	0
Accounts payable, accrued expenses, and accrued capital expenditures	732	0
Dividends payable	23,961	36,727
Due to affiliates	0	0
Deferred income	4	0
Intangible lease liabilities, net	0	0
Obligations under capital leases	0	0
Liabilities held for sale, net		0
Total liabilities	24,697	36,727
Equity:
Total equity	2,531,936	2,502,768
Total liabilities and equity	2,556,633	2,539,495
Columbia Property Trust OP (the Issuer) | Reportable Legal Entities
Real Estate Assets, at Cost:
Land	0	0
Buildings and improvements, net	2,110	219
Intangible lease assets, net	0	0
Construction in progress	0	0
Real estate assets held for sale, net		34,956
Total real estate assets	2,110	35,175
Investment in unconsolidated joint ventures	943,241	127,346
Cash and cash equivalents	5,079	16,509	14,969	10,504
Investment in subsidiaries	1,186,594	1,782,752
Tenant receivables, net of allowance	30	0
Straight-line rent receivable	0	0
Prepaid expenses and other assets	336,598	262,216
Intangible lease origination costs, net	0	0
Deferred lease costs, net	0	0
Investment in development authority bonds	0	0
Other assets held for sale, net		3,767
Total assets	2,473,652	2,227,765
Liabilities:
Line of credit and notes payable, net	899,168	447,643
Bonds payable, net	693,756	692,972
Accounts payable, accrued expenses, and accrued capital expenditures	10,325	10,395
Dividends payable	0	0
Due to affiliates	0	58
Deferred income	81	0
Intangible lease liabilities, net	0	0
Obligations under capital leases	0	0
Liabilities held for sale, net		2,651
Total liabilities	1,603,330	1,153,719
Equity:
Total equity	870,322	1,074,046
Total liabilities and equity	2,473,652	2,227,765
Non- Guarantors | Reportable Legal Entities
Real Estate Assets, at Cost:
Land	825,208	751,351
Buildings and improvements, net	2,061,309	2,120,931
Intangible lease assets, net	199,260	193,311
Construction in progress	44,742	36,188
Real estate assets held for sale, net		377,550
Total real estate assets	3,130,519	3,479,331
Investment in unconsolidated joint ventures	1	0
Cash and cash equivalents	3,796	25,156	$ 16,687	$ 19,798
Investment in subsidiaries	0	0
Tenant receivables, net of allowance	2,098	7,163
Straight-line rent receivable	92,235	64,811
Prepaid expenses and other assets	19,375	15,593
Intangible lease origination costs, net	42,959	54,279
Deferred lease costs, net	141,096	125,799
Investment in development authority bonds	120,000	120,000
Other assets held for sale, net		41,814
Total assets	3,552,079	3,933,946
Liabilities:
Line of credit and notes payable, net	715,327	704,585
Bonds payable, net	0	0
Accounts payable, accrued expenses, and accrued capital expenditures	113,949	120,633
Dividends payable	0	0
Due to affiliates	2,340	1,534
Deferred income	18,396	19,694
Intangible lease liabilities, net	27,218	33,375
Obligations under capital leases	120,000	120,000
Liabilities held for sale, net		177,497
Total liabilities	997,230	1,177,318
Equity:
Total equity	2,554,849	2,756,628
Total liabilities and equity	$ 3,552,079	$ 3,933,946

Financial Information for Par80

Financial Information for Parent Guarantor, Other Guarantor Subsidiaries, and Non-Guarantor Subsidiaries (Consolidating Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Rental income									$ 257,059	$ 366,186	$ 436,048
Tenant reimbursements									23,511	69,770	99,655
Hotel income									1,339	22,661	24,309
Asset and property management fee income									3,782	2,122	605
Other property income									3,309	12,804	5,448
Revenues	$ 71,625	$ 60,362	$ 74,857	$ 82,156	$ 105,768	$ 113,266	$ 127,930	$ 126,579	289,000	473,543	566,065
Expenses:
Property operating costs									87,805	154,968	188,078
Hotel operating costs									2,089	18,686	19,615
Asset and Property Management Fee Expenses:
Related-party									0	0	0
Other									918	1,415	1,816
Depreciation									80,394	108,543	131,490
Amortization									32,403	56,775	87,128
General and administrative – corporate									34,966	33,876	29,683
General and administrative – joint venture									1,454	0	0
Acquisition expenses									0	0	3,675
Costs and expenses									240,029	374,263	461,485
Real estate operating income (loss)									48,971	99,280	104,580
Other Income (Expense):
Interest expense									(60,516)	(67,609)	(85,296)
Interest and other income									9,529	7,288	7,254
Loss on interest rate swaps									0	0	(1,110)
Loss on the early extinguishment of debt		102,400							(325)	(18,997)	(3,149)
Nonoperating income (expense)									(51,312)	(79,318)	(82,301)
Income (loss) before income tax, unconsolidated joint ventures, and gains on sales of real estate assets									(2,341)	19,962	22,279
Income tax expense									213	(445)	(378)
Income (loss) from unconsolidated joint ventures									2,651	(7,561)	(1,142)
Income before gains on sales of real estate assets									523	11,956	20,759
Gains (loss) on sales of real estate assets									175,518	72,325	23,860
Net income	$ (1,348)	$ 101,534	$ 1,133	$ 74,722	$ 27,400	$ 36,898	$ 13,286	$ 6,697	176,041	84,281	44,619
Reportable Legal Entities | Columbia Property Trust (Parent)
Revenues:
Rental income									0	0	0
Tenant reimbursements									0	0	0
Hotel income									0	0	0
Asset and property management fee income									1,908	574	171
Other property income									0	406	0
Revenues									1,908	980	171
Expenses:
Property operating costs									0	0	0
Hotel operating costs									0	0	0
Asset and Property Management Fee Expenses:
Related-party									0	0	0
Other									0	0	0
Depreciation									0	0	0
Amortization									0	0	0
General and administrative – corporate									259	154	152
General and administrative – joint venture									0
Acquisition expenses											0
Costs and expenses									259	154	152
Real estate operating income (loss)									1,649	826	19
Other Income (Expense):
Interest expense									0	0	0
Interest and other income									16,535	14,268	14,141
Loss on interest rate swaps											0
Loss on the early extinguishment of debt									0	0	0
Nonoperating income (expense)									16,535	14,268	14,141
Income (loss) before income tax, unconsolidated joint ventures, and gains on sales of real estate assets									18,184	15,094	14,160
Income tax expense									0	0	0
Income (loss) from unconsolidated joint ventures									157,857	69,187	30,459
Income before gains on sales of real estate assets									176,041	84,281	44,619
Gains (loss) on sales of real estate assets									0	0	0
Net income									176,041	84,281	44,619
Reportable Legal Entities | Columbia Property Trust OP (the Issuer)
Revenues:
Rental income									51	3,622	2,662
Tenant reimbursements									(60)	1,963	1,316
Hotel income									0	0	0
Asset and property management fee income									0	0	0
Other property income									0	0	0
Revenues									(9)	5,585	3,978
Expenses:
Property operating costs									308	3,209	3,065
Hotel operating costs									0	0	0
Asset and Property Management Fee Expenses:
Related-party									3	154	100
Other									0	0	0
Depreciation									869	2,760	2,571
Amortization									5	364	237
General and administrative – corporate									9,048	8,566	8,754
General and administrative – joint venture									0
Acquisition expenses											11
Costs and expenses									10,233	15,053	14,738
Real estate operating income (loss)									(10,242)	(9,468)	(10,760)
Other Income (Expense):
Interest expense									(44,259)	(46,797)	(44,919)
Interest and other income									7,762	15,272	12,565
Loss on interest rate swaps											(1,101)
Loss on the early extinguishment of debt									0	(18,987)	(1,050)
Nonoperating income (expense)									(36,497)	(50,512)	(34,505)
Income (loss) before income tax, unconsolidated joint ventures, and gains on sales of real estate assets									(46,739)	(59,980)	(45,265)
Income tax expense									(1)	(20)	(25)
Income (loss) from unconsolidated joint ventures									198,620	113,105	59,165
Income before gains on sales of real estate assets									151,880	53,105	13,875
Gains (loss) on sales of real estate assets									11,050	0	(19)
Net income									162,930	53,105	13,856
Reportable Legal Entities | Non- Guarantors
Revenues:
Rental income									257,368	362,947	433,763
Tenant reimbursements									23,571	67,807	98,339
Hotel income									1,339	22,661	24,309
Asset and property management fee income									1,874	1,548	434
Other property income									3,327	12,804	5,781
Revenues									287,479	467,767	562,626
Expenses:
Property operating costs									87,857	152,142	185,390
Hotel operating costs									2,089	18,686	19,615
Asset and Property Management Fee Expenses:
Related-party									0	0	0
Other									918	1,415	1,816
Depreciation									79,525	105,783	128,919
Amortization									32,398	56,411	86,891
General and administrative – corporate									25,674	25,408	21,010
General and administrative – joint venture									1,454
Acquisition expenses											3,664
Costs and expenses									229,915	359,845	447,305
Real estate operating income (loss)									57,564	107,922	115,321
Other Income (Expense):
Interest expense									(38,238)	(50,302)	(67,076)
Interest and other income									7,213	7,238	7,247
Loss on interest rate swaps											(9)
Loss on the early extinguishment of debt									(325)	(10)	(2,099)
Nonoperating income (expense)									(31,350)	(43,074)	(61,937)
Income (loss) before income tax, unconsolidated joint ventures, and gains on sales of real estate assets									26,214	64,848	53,384
Income tax expense									214	(425)	(353)
Income (loss) from unconsolidated joint ventures									0	0	0
Income before gains on sales of real estate assets									26,428	64,423	53,031
Gains (loss) on sales of real estate assets									164,468	72,325	23,879
Net income									190,896	136,748	76,910
Consolidating Adjustments
Revenues:
Rental income									(360)	(383)	(377)
Tenant reimbursements									0	0	0
Hotel income									0	0	0
Asset and property management fee income									0	0	0
Other property income									(18)	(406)	(333)
Revenues									(378)	(789)	(710)
Expenses:
Property operating costs									(360)	(383)	(377)
Hotel operating costs									0	0	0
Asset and Property Management Fee Expenses:
Related-party									(3)	(154)	(100)
Other									0	0	0
Depreciation									0	0	0
Amortization									0	0	0
General and administrative – corporate									(15)	(252)	(233)
General and administrative – joint venture									0
Acquisition expenses											0
Costs and expenses									(378)	(789)	(710)
Real estate operating income (loss)									0	0	0
Other Income (Expense):
Interest expense									21,981	29,490	26,699
Interest and other income									(21,981)	(29,490)	(26,699)
Loss on interest rate swaps											0
Loss on the early extinguishment of debt									0	0	0
Nonoperating income (expense)									0	0	0
Income (loss) before income tax, unconsolidated joint ventures, and gains on sales of real estate assets									0	0	0
Income tax expense									0	0	0
Income (loss) from unconsolidated joint ventures									(353,826)	(189,853)	(90,766)
Income before gains on sales of real estate assets									(353,826)	(189,853)	(90,766)
Gains (loss) on sales of real estate assets									0	0	0
Net income									$ (353,826)	$ (189,853)	$ (90,766)

Financial Information for Par81

Financial Information for Parent Guarantor, Other Guarantor Subsidiaries, and Non-Guarantor Subsidiaries (Consolidating Statements of Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Net income	$ (1,348)	$ 101,534	$ 1,133	$ 74,722	$ 27,400	$ 36,898	$ 13,286	$ 6,697	$ 176,041	$ 84,281	$ 44,619
Market value adjustment to interest rate swap									1,786	1,553	(1,570)
Settlement of interest rate swap									0	0	1,102
Comprehensive income									177,827	85,834	44,151
Reportable Legal Entities | Columbia Property Trust (Parent)
Condensed Financial Statements, Captions [Line Items]
Net income									176,041	84,281	44,619
Market value adjustment to interest rate swap									1,786	1,553	(1,570)
Settlement of interest rate swap											1,102
Comprehensive income									177,827	85,834	44,151
Reportable Legal Entities | Columbia Property Trust OP (the Issuer)
Condensed Financial Statements, Captions [Line Items]
Net income									162,930	53,105	13,856
Market value adjustment to interest rate swap									1,786	1,553	(1,570)
Settlement of interest rate swap											1,102
Comprehensive income									164,716	54,658	13,388
Reportable Legal Entities | Non- Guarantors
Condensed Financial Statements, Captions [Line Items]
Net income									190,896	136,748	76,910
Market value adjustment to interest rate swap									0	0	0
Settlement of interest rate swap											0
Comprehensive income									190,896	136,748	76,910
Consolidating Adjustments
Condensed Financial Statements, Captions [Line Items]
Net income									(353,826)	(189,853)	(90,766)
Market value adjustment to interest rate swap									(1,786)	(1,553)	1,570
Settlement of interest rate swap											(1,102)
Comprehensive income									$ (355,612)	$ (191,406)	$ (90,298)

Financial Information for Par82

Financial Information for Parent Guarantor, Other Guarantor Subsidiaries, and Non-Guarantor Subsidiaries (Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	$ 61,924	$ 193,091	$ 223,080
Cash Flows From Investing Activities:
Net proceeds from sale of real estate	737,631	613,732	596,734
Investment in real estate and related assets	(718,296)	(71,907)	(1,167,933)
Investments in unconsolidated joint ventures	(369,043)	(16,212)	(5,500)
Distributions in excess of earnings from unconsolidated joint ventures	1,985	0	0
Distributions from (Investments in) subsidiaries	0	0	0
Net cash provided by (used in) investing activities	(347,723)	525,613	(576,699)
Cash Flows From Financing Activities:
Borrowings, net of fees	781,731	780,577	2,223,778
Repayments	(533,427)	(1,095,460)	(1,854,512)
Prepayments to settle debt and interest rate swap	0	(17,921)	(3,165)
Redemptions of common stock	(59,462)	(53,986)	(17,057)
Distributions	(109,561)	(148,474)	(112,570)
Net cash provided by (used in) financing activities	79,281	(535,264)	236,474
Net increase (decrease) in cash and cash equivalents	(206,518)	183,440	(117,145)
Cash and cash equivalents, beginning of period	216,085	32,645	149,790
Cash and cash equivalents, end of period	9,567	216,085	32,645
Reportable Legal Entities | Columbia Property Trust (Parent)
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	3,966	53,980	15,743
Cash Flows From Investing Activities:
Net proceeds from sale of real estate	0	0	0
Investment in real estate and related assets	0	0	0
Investments in unconsolidated joint ventures	0	0	0
Distributions in excess of earnings from unconsolidated joint ventures	0
Distributions from (Investments in) subsidiaries	(8,671)	321,911	(4,615)
Net cash provided by (used in) investing activities	(8,671)	321,911	(4,615)
Cash Flows From Financing Activities:
Borrowings, net of fees	0	0	0
Repayments	0	0	0
Prepayments to settle debt and interest rate swap		0	0
Redemptions of common stock	(59,462)	(53,986)	(17,057)
Distributions	(109,561)	(148,474)	(112,570)
Net cash provided by (used in) financing activities	(169,023)	(202,460)	(129,627)
Net increase (decrease) in cash and cash equivalents	(173,728)	173,431	(118,499)
Cash and cash equivalents, beginning of period	174,420	989	119,488
Cash and cash equivalents, end of period	692	174,420	989
Increase (decrease) in net proceeds from sales of real estate		(603,700)	(72,400)
Increase (decrease) in distributions from subsidiaries		321,900
Increase (decrease) in borrowings, net of fees		(781,400)
Increase (decrease) in debt repayments		1,090,000
Increase (decrease) in prepayments to settle debt and interest rate swap		17,900
Increase (decrease) in investments in real estate and related assets			57,200
Increase (decrease) in investments in subsidiaries			1,061,100
Reportable Legal Entities | Columbia Property Trust OP (the Issuer)
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	(46,268)	86,846	(50,601)
Cash Flows From Investing Activities:
Net proceeds from sale of real estate	49,531	0	0
Investment in real estate and related assets	(2,203)	(2,157)	0
Investments in unconsolidated joint ventures	(369,043)	(16,212)	(5,500)
Distributions in excess of earnings from unconsolidated joint ventures	1,985
Distributions from (Investments in) subsidiaries	(97,505)	568,480	(628,393)
Net cash provided by (used in) investing activities	(417,235)	550,111	(633,893)
Cash Flows From Financing Activities:
Borrowings, net of fees	781,731	780,577	2,223,778
Repayments	(331,000)	(1,051,000)	(1,518,000)
Prepayments to settle debt and interest rate swap		(17,921)	(1,102)
Redemptions of common stock	0	0	0
Distributions	1,342	(347,073)	(15,717)
Net cash provided by (used in) financing activities	452,073	(635,417)	688,959
Net increase (decrease) in cash and cash equivalents	(11,430)	1,540	4,465
Cash and cash equivalents, beginning of period	16,509	14,969	10,504
Cash and cash equivalents, end of period	5,079	16,509	14,969
Increase (decrease) in net proceeds from sales of real estate			(524,400)
Increase (decrease) in distributions from subsidiaries		568,500
Increase (decrease) in borrowings, net of fees		781,400
Increase (decrease) in debt repayments		(1,051,000)
Increase (decrease) in prepayments to settle debt and interest rate swap		(17,900)
Increase (decrease) of distributions		(347,100)	(15,700)
Increase (decrease) in investments in real estate and related assets			1,007,500
Increase (decrease) in investments in subsidiaries			(628,400)
Reportable Legal Entities | Non- Guarantors
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	104,226	242,118	273,655
Cash Flows From Investing Activities:
Net proceeds from sale of real estate	688,100	613,732	596,734
Investment in real estate and related assets	(716,093)	(69,750)	(1,167,933)
Investments in unconsolidated joint ventures	0	0	0
Distributions in excess of earnings from unconsolidated joint ventures	0
Distributions from (Investments in) subsidiaries	0	0	0
Net cash provided by (used in) investing activities	(27,993)	543,982	(571,199)
Cash Flows From Financing Activities:
Borrowings, net of fees	0	0	0
Repayments	(202,427)	(44,460)	(336,512)
Prepayments to settle debt and interest rate swap		0	(2,063)
Redemptions of common stock	0	0	0
Distributions	104,834	(733,171)	633,008
Net cash provided by (used in) financing activities	(97,593)	(777,631)	294,433
Net increase (decrease) in cash and cash equivalents	(21,360)	8,469	(3,111)
Cash and cash equivalents, beginning of period	25,156	16,687	19,798
Cash and cash equivalents, end of period	3,796	25,156	16,687
Increase (decrease) in net proceeds from sales of real estate		603,700	596,700
Increase (decrease) in debt repayments		(39,000)
Increase (decrease) of distributions		(733,200)	633,000
Increase (decrease) in investments in real estate and related assets			(1,064,700)
Consolidating Adjustments
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	0	(189,853)	(15,717)
Cash Flows From Investing Activities:
Net proceeds from sale of real estate	0	0	0
Investment in real estate and related assets	0	0	0
Investments in unconsolidated joint ventures	0	0	0
Distributions in excess of earnings from unconsolidated joint ventures	0
Distributions from (Investments in) subsidiaries	106,176	(890,391)	633,008
Net cash provided by (used in) investing activities	106,176	(890,391)	633,008
Cash Flows From Financing Activities:
Borrowings, net of fees	0	0	0
Repayments	0	0	0
Prepayments to settle debt and interest rate swap		0	0
Redemptions of common stock	0	0	0
Distributions	(106,176)	1,080,244	(617,291)
Net cash provided by (used in) financing activities	(106,176)	1,080,244	(617,291)
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents, beginning of period	0	0	0
Cash and cash equivalents, end of period	$ 0	0	0
Increase (decrease) in distributions from subsidiaries		(890,400)
Increase (decrease) of distributions		$ 1,080,300	(617,300)
Increase (decrease) in investments in subsidiaries			$ (432,700)

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 07, 2018	Jan. 05, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Feb. 01, 2018
Subsequent Event [Line Items]
Dividend declared, per share (in dollars per share)			$ 0.2	$ 0.2	$ 0.2	$ 0.20	$ 0.30	$ 0.30	$ 0.30	$ 0.30
Subsequent Event
Subsequent Event [Line Items]
Dividends payable		$ 24
Dividend declared, per share (in dollars per share)	$ 0.20
Corporate Joint Venture | Allianz | San Francisco Joint Ventures | Subsequent Event
Subsequent Event [Line Items]
Additional ownership percentage acquired											22.50%

Schedule III - Real Estate As84

Schedule III - Real Estate Assets and Accumulated Depreciation and Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Oct. 28, 2015	Dec. 31, 2014
Real Estate and Accumulated Depreciation [Line Items]
Gross Amount at Which Carried at December 31, 2017, Total	$ 3,612,294	$ 4,243,531	$ 4,948,605		$ 5,050,482
Investment in development authority bonds	120,000	$ 120,000
Aggregate cost of land and buildings and improvements for federal income tax purposes	3,933,000
THREE GLENLAKE BUILDING
Real Estate and Accumulated Depreciation [Line Items]
Investment in development authority bonds	$ 120,000
Building Improvements | Minimum
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	5 years
Building Improvements | Maximum
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	25 years
Building | Minimum
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Building | Maximum
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	45 years
Corporate Joint Venture
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage				51.00%
Consolidated Properties
Real Estate and Accumulated Depreciation [Line Items]
Initial Costs, Land	$ 823,281
Initial Costs, Building and Improvements	2,697,937
Initial Costs, Total	3,521,218
Costs Capitalized Subsequent to Acquisition	91,076
Gross Amount at Which Carried at December 31, 2017, Land	825,208
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	2,787,086
Gross Amount at Which Carried at December 31, 2017, Total	3,612,294
Accumulated Depreciation and Amortization	$ 482,627
Consolidated Properties | ONE & THREE GLENLAKE
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 23,716
Initial Costs, Land	13,363
Initial Costs, Building and Improvements	155,465
Initial Costs, Total	168,828
Costs Capitalized Subsequent to Acquisition	2,429
Gross Amount at Which Carried at December 31, 2017, Land	13,989
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	157,268
Gross Amount at Which Carried at December 31, 2017, Total	171,257
Accumulated Depreciation and Amortization	$ 49,203
Consolidated Properties | 80 M STREET
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	26,248
Initial Costs, Building and Improvements	76,269
Initial Costs, Total	102,517
Costs Capitalized Subsequent to Acquisition	7,080
Gross Amount at Which Carried at December 31, 2017, Land	26,806
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	82,791
Gross Amount at Which Carried at December 31, 2017, Total	109,597
Accumulated Depreciation and Amortization	$ 23,439
Consolidated Properties | 263 SHUMAN BOULEVARD
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 49,000
Initial Costs, Land	7,142
Initial Costs, Building and Improvements	41,535
Initial Costs, Total	48,677
Costs Capitalized Subsequent to Acquisition	(3,344)
Gross Amount at Which Carried at December 31, 2017, Land	7,233
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	38,100
Gross Amount at Which Carried at December 31, 2017, Total	45,333
Accumulated Depreciation and Amortization	$ 15,146
Consolidated Properties | 95 COLUMBUS
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	29,061
Initial Costs, Building and Improvements	141,544
Initial Costs, Total	170,605
Costs Capitalized Subsequent to Acquisition	13,056
Gross Amount at Which Carried at December 31, 2017, Land	29,712
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	153,949
Gross Amount at Which Carried at December 31, 2017, Total	183,661
Accumulated Depreciation and Amortization	$ 60,366
Consolidated Properties | PASADENA CORPORATE PARK
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	53,099
Initial Costs, Building and Improvements	59,630
Initial Costs, Total	112,729
Costs Capitalized Subsequent to Acquisition	(893)
Gross Amount at Which Carried at December 31, 2017, Land	53,099
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	58,737
Gross Amount at Which Carried at December 31, 2017, Total	111,836
Accumulated Depreciation and Amortization	$ 17,944
Consolidated Properties | 222 EAST 41ST STREET
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	0
Initial Costs, Building and Improvements	324,520
Initial Costs, Total	324,520
Costs Capitalized Subsequent to Acquisition	(25,359)
Gross Amount at Which Carried at December 31, 2017, Land	0
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	299,161
Gross Amount at Which Carried at December 31, 2017, Total	299,161
Accumulated Depreciation and Amortization	$ 67,336
Consolidated Properties | LINDBERGH CENTER
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	0
Initial Costs, Building and Improvements	262,468
Initial Costs, Total	262,468
Costs Capitalized Subsequent to Acquisition	3,252
Gross Amount at Which Carried at December 31, 2017, Land	0
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	265,720
Gross Amount at Which Carried at December 31, 2017, Total	265,720
Accumulated Depreciation and Amortization	$ 77,417
Consolidated Properties | CRANBERRY WOODS DRIVE
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	15,512
Initial Costs, Building and Improvements	173,062
Initial Costs, Total	188,574
Costs Capitalized Subsequent to Acquisition	6,579
Gross Amount at Which Carried at December 31, 2017, Land	15,512
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	179,641
Gross Amount at Which Carried at December 31, 2017, Total	195,153
Accumulated Depreciation and Amortization	$ 46,136
Consolidated Properties | 221 MAIN STREET
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	60,509
Initial Costs, Building and Improvements	174,629
Initial Costs, Total	235,138
Costs Capitalized Subsequent to Acquisition	12,927
Gross Amount at Which Carried at December 31, 2017, Land	60,509
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	187,556
Gross Amount at Which Carried at December 31, 2017, Total	248,065
Accumulated Depreciation and Amortization	$ 27,105
Consolidated Properties | 650 CALIFORNIA STREET
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	75,384
Initial Costs, Building and Improvements	240,441
Initial Costs, Total	315,825
Costs Capitalized Subsequent to Acquisition	13,978
Gross Amount at Which Carried at December 31, 2017, Land	75,384
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	254,419
Gross Amount at Which Carried at December 31, 2017, Total	329,803
Accumulated Depreciation and Amortization	$ 28,925
Consolidated Properties | 315 PARK AVENUE SOUTH
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	119,633
Initial Costs, Building and Improvements	249,510
Initial Costs, Total	369,143
Costs Capitalized Subsequent to Acquisition	13,130
Gross Amount at Which Carried at December 31, 2017, Land	119,633
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	262,640
Gross Amount at Which Carried at December 31, 2017, Total	382,273
Accumulated Depreciation and Amortization	$ 19,204
Consolidated Properties | 116 HUNTINGTON AVENUE
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	0
Initial Costs, Building and Improvements	116,290
Initial Costs, Total	116,290
Costs Capitalized Subsequent to Acquisition	47,662
Gross Amount at Which Carried at December 31, 2017, Land	0
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	163,952
Gross Amount at Which Carried at December 31, 2017, Total	163,952
Accumulated Depreciation and Amortization	$ 16,640
Consolidated Properties | 229 WEST 43RD STREET
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	207,233
Initial Costs, Building and Improvements	292,991
Initial Costs, Total	500,224
Costs Capitalized Subsequent to Acquisition	(553)
Gross Amount at Which Carried at December 31, 2017, Land	207,233
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	292,438
Gross Amount at Which Carried at December 31, 2017, Total	499,671
Accumulated Depreciation and Amortization	$ 30,119
Consolidated Properties | 245-249 WEST 17TH STREET
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	113,149
Initial Costs, Building and Improvements	221,517
Initial Costs, Total	334,666
Costs Capitalized Subsequent to Acquisition	0
Gross Amount at Which Carried at December 31, 2017, Land	113,150
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	221,516
Gross Amount at Which Carried at December 31, 2017, Total	334,666
Accumulated Depreciation and Amortization	$ 2,210
Consolidated Properties | 218 WEST 18TH STREET
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	43,836
Initial Costs, Building and Improvements	139,077
Initial Costs, Total	182,913
Costs Capitalized Subsequent to Acquisition	0
Gross Amount at Which Carried at December 31, 2017, Land	43,836
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	139,077
Gross Amount at Which Carried at December 31, 2017, Total	182,913
Accumulated Depreciation and Amortization	$ 1,437
Consolidated Properties | 149 MADISON AVENUE
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	100.00%
Encumbrances	$ 0
Initial Costs, Land	59,112
Initial Costs, Building and Improvements	28,989
Initial Costs, Total	88,101
Costs Capitalized Subsequent to Acquisition	1,132
Gross Amount at Which Carried at December 31, 2017, Land	59,112
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	30,121
Gross Amount at Which Carried at December 31, 2017, Total	89,233
Accumulated Depreciation and Amortization	0
Consolidated Properties | ONE GLENLAKE PARKWAY
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	$ 23,700
Consolidated Properties | Minimum | ONE & THREE GLENLAKE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | 80 M STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | 263 SHUMAN BOULEVARD
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | 95 COLUMBUS
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | PASADENA CORPORATE PARK
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | 222 EAST 41ST STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | LINDBERGH CENTER
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | CRANBERRY WOODS DRIVE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | 221 MAIN STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | 650 CALIFORNIA STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | 315 PARK AVENUE SOUTH
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | 116 HUNTINGTON AVENUE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | 229 WEST 43RD STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | 245-249 WEST 17TH STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | 218 WEST 18TH STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Minimum | 149 MADISON AVENUE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Consolidated Properties | Maximum | ONE & THREE GLENLAKE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | 80 M STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | 263 SHUMAN BOULEVARD
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | 95 COLUMBUS
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | PASADENA CORPORATE PARK
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | 222 EAST 41ST STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	45 years
Consolidated Properties | Maximum | LINDBERGH CENTER
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | CRANBERRY WOODS DRIVE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | 221 MAIN STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | 650 CALIFORNIA STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | 315 PARK AVENUE SOUTH
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | 116 HUNTINGTON AVENUE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | 229 WEST 43RD STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | 245-249 WEST 17TH STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | 218 WEST 18TH STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Consolidated Properties | Maximum | 149 MADISON AVENUE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Unconsolidated Properties
Real Estate and Accumulated Depreciation [Line Items]
Initial Costs, Land	$ 420,340
Initial Costs, Building and Improvements	1,677,932
Initial Costs, Total	2,098,272
Costs Capitalized Subsequent to Acquisition	(148,977)
Gross Amount at Which Carried at December 31, 2017, Land	420,605
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	1,528,690
Gross Amount at Which Carried at December 31, 2017, Total	1,949,295
Accumulated Depreciation and Amortization	67,388
Initial cost of land, buildings and improvements net of encumbrances	$ 2,025,000
Unconsolidated Properties | MARKET SQUARE
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	51.00%
Encumbrances	$ 325,000
Initial Costs, Land	152,629
Initial Costs, Building and Improvements	450,757
Initial Costs, Total	603,386
Costs Capitalized Subsequent to Acquisition	(41,591)
Gross Amount at Which Carried at December 31, 2017, Land	152,629
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	409,166
Gross Amount at Which Carried at December 31, 2017, Total	561,795
Accumulated Depreciation and Amortization	$ 29,483
Unconsolidated Properties | UNIVERSITY CIRCLE
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	77.50%
Encumbrances	$ 0
Initial Costs, Land	27,493
Initial Costs, Building and Improvements	278,288
Initial Costs, Total	305,781
Costs Capitalized Subsequent to Acquisition	(99,466)
Gross Amount at Which Carried at December 31, 2017, Land	27,757
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	178,558
Gross Amount at Which Carried at December 31, 2017, Total	206,315
Accumulated Depreciation and Amortization	$ 2,839
Unconsolidated Properties | 333 MARKET STREET
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	77.50%
Encumbrances	$ 0
Initial Costs, Land	114,483
Initial Costs, Building and Improvements	292,840
Initial Costs, Total	407,323
Costs Capitalized Subsequent to Acquisition	(41,229)
Gross Amount at Which Carried at December 31, 2017, Land	114,484
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	251,610
Gross Amount at Which Carried at December 31, 2017, Total	366,094
Accumulated Depreciation and Amortization	$ 4,038
Unconsolidated Properties | 114 FIFTH AVE
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	49.50%
Encumbrances	$ 0
Initial Costs, Land	0
Initial Costs, Building and Improvements	383,694
Initial Costs, Total	383,694
Costs Capitalized Subsequent to Acquisition	1,824
Gross Amount at Which Carried at December 31, 2017, Land	0
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	385,518
Gross Amount at Which Carried at December 31, 2017, Total	385,518
Accumulated Depreciation and Amortization	$ 27,165
Unconsolidated Properties | 1800 M STREET
Real Estate and Accumulated Depreciation [Line Items]
Ownership percentage	55.00%
Encumbrances	$ 0
Initial Costs, Land	125,735
Initial Costs, Building and Improvements	272,353
Initial Costs, Total	398,088
Costs Capitalized Subsequent to Acquisition	31,485
Gross Amount at Which Carried at December 31, 2017, Land	125,735
Gross Amount at Which Carried at December 31, 2017, Buildings and Improvements	303,838
Gross Amount at Which Carried at December 31, 2017, Total	429,573
Accumulated Depreciation and Amortization	$ 3,863
Unconsolidated Properties | Minimum | MARKET SQUARE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Unconsolidated Properties | Minimum | UNIVERSITY CIRCLE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Unconsolidated Properties | Minimum | 333 MARKET STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Unconsolidated Properties | Minimum | 114 FIFTH AVE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Unconsolidated Properties | Minimum | 1800 M STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	0 years
Unconsolidated Properties | Maximum | MARKET SQUARE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Unconsolidated Properties | Maximum | UNIVERSITY CIRCLE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Unconsolidated Properties | Maximum | 333 MARKET STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Unconsolidated Properties | Maximum | 114 FIFTH AVE
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Unconsolidated Properties | Maximum | 1800 M STREET
Real Estate and Accumulated Depreciation [Line Items]
Real estate and accumulated depreciation, life used for depreciation	40 years
Corporate | Consolidated Properties
Real Estate and Accumulated Depreciation [Line Items]
Gross Amount at Which Carried at December 31, 2017, Total	$ 3,200

Schedule III - Real Estate As85

Schedule III - Real Estate Assets and Accumulated Depreciation and Amortization (Rollforward) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jul. 05, 2017	Oct. 28, 2015
Real Estate:
Balance at beginning of year	$ 4,243,531	$ 4,948,605	$ 5,050,482
Additions to/improvements of real estate	698,567	41,848	1,162,068
Sale/transfer of real estate	(1,285,915)	(673,164)	(1,188,083)
Write-offs of building and tenant improvements	(3,087)	(5,559)	(1,552)
Write-offs of intangible assets	(14,432)	(30,435)	(12,614)
Write-offs of fully depreciated assets	(26,370)	(37,764)	(61,696)
Balance at end of year	3,612,294	4,243,531	4,948,605
Accumulated Depreciation and Amortization:
Balance at beginning of year	729,025	863,724	973,920
Depreciation and amortization expense	97,732	140,823	183,492
Sale/transfer of real estate	(302,157)	(203,248)	(221,481)
Write-offs of tenant improvements	(1,406)	(4,336)	(948)
Write-offs of intangible assets	(14,197)	(30,174)	(9,563)
Write-offs of fully depreciated assets	(26,370)	(37,764)	(61,696)
Balance at end of year	$ 482,627	$ 729,025	$ 863,724
Corporate Joint Venture
Accumulated Depreciation and Amortization:
Ownership percentage					51.00%
University Circle & 333 Market Street | Corporate Joint Venture
Accumulated Depreciation and Amortization:
Percentage of real estate transferred	100.00%
Ownership percentage	77.50%			100.00%
Market Square Joint Venture | Corporate Joint Venture
Accumulated Depreciation and Amortization:
Ownership percentage	51.00%				100.00%