SBA Communications (SBAC) 10-Q 8 Nov 18 2018 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 31, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Entity Registrant Name	SBA COMMUNICATIONS CORP
Entity Central Index Key	1,034,054
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		113,321,450
Trading Symbol	SBAC

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 136,221	$ 68,783
Restricted cash	24,700	32,924
Accounts receivable, net	89,302	90,673
Costs and estimated earnings in excess of billings on uncompleted contracts	17,799	17,437
Prepaid expenses and other current assets	59,641	49,716
Total current assets	327,663	259,533
Property and equipment, net	2,787,714	2,812,346
Intangible assets, net	3,387,955	3,598,131
Other assets	710,491	650,195
Total assets	7,213,823	7,320,205
Current liabilities:
Accounts payable	32,087	33,334
Accrued expenses	68,129	69,862
Current maturities of long-term debt	24,000	20,000
Deferred revenue	96,577	97,969
Accrued interest	34,186	48,899
Other current liabilities	10,533	8,841
Total current liabilities	265,512	278,905
Long-term liabilities:
Long-term debt, net	9,710,145	9,290,686
Other long-term liabilities	383,249	349,728
Total long-term liabilities	10,093,394	9,640,414
Shareholders' deficit:
Preferred stock - par value $.01, 30,000 shares authorized, no shares issued or outstanding
Common stock - Class A, par value $.01, 400,000 shares authorized, 114,244 and 116,446 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively	1,142	1,164
Additional paid-in capital	2,233,793	2,167,470
Accumulated deficit	(4,851,501)	(4,388,288)
Accumulated other comprehensive loss, net	(528,517)	(379,460)
Total shareholders' deficit	(3,145,083)	(2,599,114)
Total liabilities and shareholders' deficit	$ 7,213,823	$ 7,320,205

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	30,000,000	30,000,000
Preferred stock, shares issued	0	0
Common Stock [Member]
Common stock - Class A, par value	$ 0.01	$ 0.01
Common stock - Class A, shares authorized	400,000,000	400,000,000
Common stock - Class A, shares issued	114,244,000	116,446,000
Common stock - Class A, shares outstanding	114,244,000	116,446,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Site leasing		$ 435,260	$ 408,538	$ 1,295,686	$ 1,209,089
Site development		31,961	25,407	86,160	75,513
Total revenues		467,221	433,945	1,381,846	1,284,602
Cost of revenues (exclusive of depreciation, accretion, and amortization shown below):
Cost of site leasing		92,294	90,351	278,800	269,070
Cost of site development		24,447	21,117	67,693	62,713
Selling, general, and administrative	[1]	34,908	32,559	106,901	100,177
Acquisition related adjustments and expenses		2,995	1,583	9,171	6,857
Asset impairment and decommission costs		6,868	9,417	22,778	25,908
Depreciation, accretion, and amortization		167,703	161,907	502,659	480,457
Total operating expenses		329,215	316,934	988,002	945,182
Operating income		138,006	117,011	393,844	339,420
Other income (expense):
Interest income		2,006	2,505	4,972	8,648
Interest expense		(95,717)	(81,357)	(278,278)	(237,415)
Non-cash interest expense		(632)	(725)	(2,002)	(2,146)
Amortization of deferred financing fees		(4,980)	(4,957)	(15,265)	(16,603)
Loss from extinguishment of debt, net				(14,443)	(1,961)
Other (expense) income, net		(24,518)	20,062	(110,175)	16,218
Total other expense		(123,841)	(64,472)	(415,191)	(233,259)
Income (loss) before income taxes		14,165	52,539	(21,347)	106,161
Benefit (provision) for income taxes		1,979	(3,378)	11,645	(10,167)
Net income (loss)		$ 16,144	$ 49,161	$ (9,702)	$ 95,994
Net income (loss) per common share
Basic		$ 0.14	$ 0.41	$ (0.08)	$ 0.80
Diluted		$ 0.14	$ 0.41	$ (0.08)	$ 0.79
Weighted average number of common shares
Basic		114,597	119,746	115,378	120,745
Diluted		116,114	121,026	115,378	121,727
[1]	Includes non-cash compensation of $10,261 and $9,213 for the three months ended September 30, 2018 and 2017, respectively, and $31,188 and $28,069 for the nine months ended September 30, 2018 and 2017, respectively.

Consolidated Statements of Op_2

Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Non-cash compensation expense			$ 32,140	$ 28,894
Selling, General And Administrative [Member]
Non-cash compensation expense	$ 10,261	$ 9,213	$ 31,188	$ 28,069

Consolidated Statements of Comp

Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Consolidated Statements of Comprehensive (Loss) Income [Abstract]
Net income (loss)	$ 16,144	$ 49,161	$ (9,702)	$ 95,994
Foreign currency translation adjustments	(27,598)	36,472	(149,057)	27,734
Comprehensive (loss) income	$ (11,454)	$ 85,633	$ (158,759)	$ 123,728

Consolidated Statement of Share

Consolidated Statement of Shareholders' Deficit - 9 months ended Sep. 30, 2018 - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]Class A Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Total
BALANCE at Dec. 31, 2017	$ 1,164	$ 2,167,470	$ (4,388,288)	$ (379,460)	$ (2,599,114)
BALANCE, Shares at Dec. 31, 2017	116,446
Net loss			(9,702)		(9,702)
Common stock issued in connection with stock purchase/option plans	$ 6	33,523			33,529
Common stock issued in connection with stock purchase/option plans, Shares	611
Non-cash stock compensation		32,800			32,800
Repurchase and retirement of common stock	$ (28)		(453,511)		(453,539)
Repurchase and retirement of common stock, Shares	(2,813)
Foreign currency translation adjustments				(149,057)	(149,057)
BALANCE at Sep. 30, 2018	$ 1,142	$ 2,233,793	$ (4,851,501)	$ (528,517)	$ (3,145,083)
BALANCE, Shares at Sep. 30, 2018	114,244

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net (loss) income	$ (9,702)	$ 95,994
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation, accretion, and amortization	502,659	480,457
Non-cash asset impairment and decommission costs	22,146	22,316
Non-cash compensation expense	32,140	28,894
Amortization of deferred financing fees	15,265	16,603
Loss (gain) on remeasurement of U.S. dollar denominated intercompany loans	113,138	(11,649)
Loss from extinguishment of debt	14,087	1,961
Deferred income tax benefit	(27,925)	(1,220)
Other non-cash items reflected in the Statements of Operations	2,022	237
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable and costs and estimated earnings in excess of billings on uncompleted contracts, net	(4,655)	(11,950)
Prepaid expenses and other assets	(28,061)	(18,168)
Accounts payable and accrued expenses	(2,496)	4,846
Accrued interest	(14,813)	(24,836)
Other liabilities	10,338	7,987
Net cash provided by operating activities	624,143	591,472
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions	(403,835)	(161,007)
Capital expenditures	(104,966)	(106,310)
Purchase of investments	(99,823)	(382)
Proceeds from sale of investments	95,890
Other investing activities	(7,583)	(23,216)
Net cash used in investing activities	(520,317)	(290,915)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under Revolving Credit Facility	805,000	415,000
Repayments under Revolving Credit Facility	(725,000)	(375,000)
Repayment of Tower Securities	(755,000)	(610,000)
Proceeds from issuance of Tower Securities, net of fees	631,479	749,811
Proceeds from Term Loans, net of fees	2,377,264
Repayment of Term Loans	(1,941,000)	(15,000)
Repurchase and retirement of common stock	(453,539)	(523,370)
Other financing activities	29,607	40,957
Net cash used in financing activities	(31,189)	(317,602)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	(13,608)	3,537
NET CHANGE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	59,029	(13,508)
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH:
Beginning of period	104,295	185,970
End of period	163,324	172,462
Cash paid during the period for:
Interest	293,372	262,257
Income taxes	16,525	11,323
SUPPLEMENTAL DISCLOSURE OF NON-CASH ACTIVITIES:
Assets acquired through capital leases	$ 1,142	$ 254
Common stock issued in connection with acquisitions		63,313

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Basis of Presentation [Abstract]
Basis of Presentation	1. BASIS OF PRESENTATION The accompanying consolidated financial statements should be read in conjunction with the Annual Report on Form 10-K for the fiscal year ended December 31, 2017 for SBA Communications Corporation and its subsidiaries (the “Company”). These financial statements have been prepared in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X and, therefore, omit or condense certain footnotes and other information normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States. In the opinion of the Company’s management, all adjustments (consisting of normal recurring accruals) considered necessary for fair financial statement presentation have been made. The results of operations for an interim period may not give a true indication of the results for the year. Certain reclassifications have been made to prior year amounts or balances to conform to the presentation adopted in the current year. The preparation of financial statements requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. While the Company believes that such estimates are fair when considered in conjunction with the consolidated financial statements and accompanying notes, the actual amounts, when known, may vary from these estimates. Revenue Recognition and Accounts Receivable Revenue from site leasing is recognized on a straight-line basis over the current term of the related lease agreements, which are generally five to ten years. Receivables recorded related to the straight-line impact of site leases are reflected in other assets on the Consolidated Balance Sheets. Rental amounts received in advance are recorded as deferred revenue on the Consolidated Balance Sheets. Revenues from site leasing represent 94% of the Company’s total revenues. Site development projects in which the Company performs consulting services include contracts on a fixed price basis that are billed at contractual rates. Revenue is recognized over time based on milestones achieved, which are determined based on costs incurred. Amounts billed in advance (collected or uncollected) are recorded as deferred revenue on the Consolidated Balance Sheets. Revenue from construction projects is recognized over time, determined by the percentage of cost incurred to date compared to management’s estimated total cost for each contract. This method is used because management considers total cost to be the best available measure of progress on the contracts. These amounts are based on estimates, and the uncertainty inherent in the estimates initially is reduced as work on the contracts nears completion. Refer to Note 8 for further detail of costs and estimated earnings in excess of billings on uncompleted contracts. Provisions for estimated losses on uncompleted contracts are made in the period in which such losses are determined to be probable. The site development segment represents approximately 6% of the Company’s total revenues. The Company accounts for site development revenue in accordance with ASC 606, Revenue from Contracts with Customers, which was adopted on January 1, 2018 by applying the modified retrospective transition method. Payment terms do not result in any significant financing arrangements. Furthermore, these contracts do not typically include variable consideration; therefore, the transaction price that is recognized over time is generally the amount of the total contract. The cumulative effect of initially applying the new revenue standard had no impact on the Company’s financial results. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. The adoption of the new standard will have no impact to net income on an ongoing basis. The accounts receivable balance was $89.3 million and $90.7 million as of September 30, 2018 and December 31, 2017 , respectively, of which $23.2 million and $20.8 million related to the site development segment as of September 30, 2018 and December 31, 2017 , respectively. The Company performs periodic credit evaluations of its customers. In addition, the Company monitors collections and payments from its customers and maintains a provision for estimated credit losses based upon historical experience, specific customer collection issues identified, and past due balances as determined based on contractual terms. Interest is charged on outstanding receivables from customers on a case by case basis in accordance with the terms of the respective contracts or agreements with those customers. Amounts determined to be uncollectible are written off against the allowance for doubtful accounts in the period in which uncollectibility is determined to be probable. Refer to Note 14 for further detail of the site development segment. Foreign Currency Translation All assets and liabilities of foreign subsidiaries that do not utilize the U.S. dollar as its functional currency are translated at period-end rates of exchange, while revenues and expenses are translated at monthly average rates of exchange prevailing during the period. Unrealized remeasurement gains and losses are reported as foreign currency translation adjustments through Accumulated Other Comprehensive Loss in the accompanying Consolidated Statement of Shareholders’ Deficit. For foreign subsidiaries where the U.S. dollar is the functional currency, monetary assets and liabilities of such subsidiaries, which are not denominated in U.S. dollars, are remeasured at exchange rates in effect at the balance sheet date, and revenues and expenses are remeasured at monthly average rates prevailing during the year. Unrealized translation gains and losses are reported as other income (expense), net in the Consolidated Statement of Operations. The Argentinean economy was deemed to be highly inflationary as of the second quarter of 2018 and, as a result, the Company adopted highly inflationary accounting as of July 1, 2018 for its subsidiary in Argentina. Under highly inflationary accounting, the functional currency of its subsidiary in Argentina became the U.S. Dollar. All monetary and non-monetary assets and liabilities were remeasured at the U.S. Dollar to Argentinean Peso exchange rate of 1 to 28.9 as of June 30, 2018. These amounts became the new basis for those assets and liabilities as of July 1, 2018. Non-monetary assets and liabilities, as well as the corresponding income statement activities such as depreciation, amortization and equity, will continue to be measured at the historical exchange rate. This change did not have a material impact on the Company’s financial statements as Argentina’s assets and revenue are each less than 1% of consolidated assets and revenue , respectively. Intercompany Loans Subject to Remeasurement The Company has two wholly owned subsidiaries, Brazil Shareholder I, LLC, a Florida limited liability company, and SBA Torres Brasil, Limitada, a limited liability company existing under the laws of the Republic of Brazil, which have entered into intercompany loan agreements pursuant to which the entities may from time to time agree to lend/borrow amounts under the terms of each agreement. The first agreement entered into in November 2014 was for $750.0 million and was created to fund the acquisition of 1,641 towers in Brazil. The second agreement entered into in December 2017 was for $500.0 million and was created to fund the acquisition of 941 towers in Brazil. In accordance with Accounting Standards Codification (ASC) 830, the Company remeasures foreign denominated intercompany loans with the corresponding change in the balance being recorded in Other income (expense), net in the Consolidated Statement of Operations as settlement is anticipated or planned in the foreseeable future. The Company recorded a $25.9 million loss and an $18.4 million gain on the remeasurement of intercompany loans for the three months ended September 30, 2018 and 2017 , respectively, and a $113.1 million loss and an $11.6 million gain on the remeasurement of intercompany loans for the nine months ended September 30, 2018 and 2017 , respectively, due to changes in foreign exchange rates. As of September 30, 2018 , the aggregate amount outstanding under the two intercompany loan agreements with the Company’s Brazilian subsidiary was $536.9 million. Recent Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU 2016-02, Leases. The standard requires lessees to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments for all leases with a term greater than 12 months. The accounting for lessors remains largely unchanged from existing guidance. This standard is effective for annual and interim periods beginning after December 15, 2018. Early adoption is permitted; however, the Company does not currently plan to early adopt. The Company has established a cross functional project plan and is in the process of testing key system functionality developed in order to account for the new standard. The Company expects this guidance to have a material impact on its consolidated balance sheet due to the recognition of right-of-use assets and lease liabilities for its ground leases. The Company does not expect adoption to have a significant impact on its lease classification, a material impact on its consolidated statement of operations, or a notable impact on its liquidity. Additionally, the sta ndard will have no impact on the Company’s debt-covenant compliance under its current agreements. In July 2018, the FASB issued additional guidance on the accounting for leases. The guidance provides companies with another transition method that allows entities to recognize a cumulative-effect adjustment to the opening balance of retained earnings as of the date of adoption. Under this method, previously presented years’ financial positions and results would not be adjusted. The Company expects it will adopt this alternative transition method. The new guidance also provides lessors with a practical expedient, by class of underlying asset, to not separate non-lease components from the associated lease component if (1) the non-lease components would otherwise be accounted for under the new revenue recognition standard, (2) both the timing and pattern of transfer are the same for the non-lease components and associated lease component, and (3) if accounted for separately, the lease component would be classified as an operating lease. The Company is assessing the use of this practical expedient in its accounting for leases. 

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Measurements [Abstract]
Fair Value Measurements	2. FAIR VALUE MEASUREMENTS Items Measured at Fair Value on a Recurring Basis — The Company’s earnout liabilities related to business combinations are measured at fair value on a recurring basis using Level 3 inputs and are recorded in Accrued expenses in the accompanying Consolidated Balance Sheets. Changes in estimates are recorded in Acquisition related adjustments and expenses in the accompanying Consolidated Statement of Operations. The Company determines the fair value of earnouts (contingent consideration) and any subsequent changes in fair value using a discounted probability-weighted approach using Level 3 inputs. Level 3 valuations rely on unobservable inputs for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability. The fair value of the earnouts is reviewed quarterly and is based on the payments the Company expects to make based on historical internal observations related to the anticipated performance of the underlying assets. The Company’s estimate of the fair value of its obligation contained in acquisitions prior to January 1, 2017 (adoption of ASU 2017-01) was $1.9 million and $2.5 million as of September 30, 2018 and December 31, 2017 , respectively. The maximum potential obligation related to the performance targets for these acquisitions was $2.4 million and $3.1 million as of September 30, 2018 and December 31, 2017 , respectively. The maximum potential obligation related to the performance targets for acquisitions after January 1, 2017, which have not been recorded on the Company’s Consolidated Balance Sheet, were $14.2 million and $11.1 million as of September 30, 2018 and December 31, 2017 , respectively. The Company’s asset retirement obligations are measured at fair value on a recurring basis using Level 3 inputs and are recorded in Other long-term liabilities in the accompanying Consolidated Balance Sheets. The fair value of the asset retirement obligations is calculated using a discounted cash flow model. Items Measured at Fair Value on a Nonrecurring Basis — The Company’s long-lived and intangible assets are measured at fair value on a nonrecurring basis using Level 3 inputs. The Company considers many factors and makes certain assumptions when making this assessment, including but not limited to: general market and economic conditions, historical operating results, geographic location, lease-up potential and expected timing of lease-up. The fair value of the long-lived and intangible assets is calculated using a discounted cash flow model. Asset impairment and decommission costs for all periods presented and the related impaired assets primarily relate to the Company’s site leasing operating segment. The following summarizes the activity of asset impairment and decommission costs (in thousands):     For the three months For the nine months  ended September 30, ended September 30,  2018 2017 2018 2017   Asset impairment (1) $ 2,909 $ 4,128 $ 13,291 $ 10,162  Write-off of carrying value of decommissioned towers 3,561 4,496 7,932 12,143  Other (including third party decommission costs) 398 793 1,555 3,603  Total asset impairment and decommission costs $ 6,868 $ 9,417 $ 22,778 $ 25,908  (1) Represents impairment charges resulting from the Company’s regular analysis of whether the future cash flows from certain towers are adequate to recover the carrying value of the investment in those towers. Fair Value of Financial Instruments — The carrying values of cash and cash equivalents, accounts receivable, restricted cash, accounts payable, and short-term investments approximate their estimated fair values due to the short maturity of these instruments. Short-term investments consisted of $0.2 million in Treasury securities as of December 31, 2017 . The Company’s estimate of the fair value of its held-to-maturity investments in treasury and corporate bonds, including current portion, are based primarily upon Level 1 reported market values. As of September 30, 2018 , the carrying value and fair value of the held-to-maturity investments were $0.2 million. As of December 31, 2017 , the carrying value and fair value of the held-to-maturity investments, including current portion, were $0.5 million. The current portion is recorded in Prepaid and other current assets in the accompanying Consolidated Balance Sheets, while held-to-maturity investments are recorded in Other assets. For the three and nine months ended September 30, 2018, the Company purchased and sold $95.0 million of short-term investments. The Company determines fair value of its debt instruments utilizing various Level 2 sources including quoted prices and indicative quotes (non-binding quotes) from brokers that require judgment to interpret market information including implied credit spreads for similar borrowings on recent trades or bid/ask prices. The fair value of the Revolving Credit Facility is considered to approximate the carrying value because the interest payments are based on Eurodollar rates that reset monthly or more frequently. The Company does not believe its credit risk has changed materially from the date the applicable Eurodollar Rate was set for the Revolving Credit Facility ( 112.5 to 175.0 basis points). Refer to Note 10 for the fair values, principal balances, and carrying values of the Company’s debt instruments.

Restricted Cash

Restricted Cash	9 Months Ended
	Sep. 30, 2018
Restricted Cash [Abstract]
Restricted Cash	3. RESTRICTED CASH The cash, cash equivalents, and restricted cash balances on the consolidated statement of cash flows consists of the following:    As of As of  September 30, 2018 December 31, 2017 Included on Balance Sheet   (in thousands)  Cash and cash equivalents $ 136,221 $ 68,783  Securitization escrow accounts 24,504 32,699 Restricted cash - current asset  Payment and performance bonds 196 225 Restricted cash - current asset  Surety bonds and workers compensation 2,403 2,588 Other assets - noncurrent  Total cash, cash equivalents, and restricted cash $ 163,324 $ 104,295  Pursuant to the terms of the Tower Securities (see Note 10), the Company is required to establish a securitization escrow account, held by the indenture trustee, into which all rents and other sums due on the towers that secure the Tower Securities are directly deposited by the lessees. These restricted cash amounts are used to fund reserve accounts for the payment of (1) debt service costs, (2) ground rents, real estate and personal property taxes and insurance premiums related to towers, (3) trustee and servicing expenses, and (4) management fees. The restricted cash in the securitization escrow account in excess of required reserve balances is subsequently released to the Borrowers (as defined in Note 10) monthly, provided that the Borrowers are in compliance with their debt service coverage ratio and that no event of default has occurred. All monies held by the indenture trustee are classified as restricted cash on the Company’s Consolidated Balance Sheets. Payment and performance bonds relate primarily to collateral requirements for tower construction currently in process by the Company. Cash is pledged as collateral related to surety bonds issued for the benefit of the Company or its affiliates in the ordinary course of business and primarily related to the Company’s tower removal obligations. As of September 30, 2018 and December 31, 2017 , the Company had $40.4 million and $39.5 million in surety, payment and performance bonds, respectively, for which no collateral was required to be posted. The Company periodically evaluates the collateral posted for its bonds to ensure that it meets the minimum requirements. As of September 30, 2018 and December 31, 2017 , the Company had also pledged $2.3 million and $2.5 million, respectively, as collateral related to its workers compensation policy.

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets and Other Assets	9 Months Ended
	Sep. 30, 2018
Prepaid Expenses and Other Current Assets and Other Assets [Abstract]
Prepaid Expenses and Other Current Assets and Other Assets	4. PREPAID EXPENSES AND OTHER CURRENT ASSETS AND OTHER ASSETS The Company’s prepaid expenses and other current assets are comprised of the following:     As of As of  September 30, 2018 December 31, 2017   (in thousands)  Prepaid ground rent $ 31,323 $ 32,505  Loan receivables 10,877 948  Other 17,441 16,263  Total prepaid expenses and other current assets $ 59,641 $ 49,716  The Company’s other assets are comprised of the following:     As of As of  September 30, 2018 December 31, 2017   (in thousands)  Prepaid ground rent $ 252,506 $ 220,493  Straight-line rent receivable 317,422 313,650  Loan receivables 45,300 52,383  Deferred lease costs, net 26,682 27,703  Deferred tax asset - long term 28,130 1,670  Other 40,451 34,296  Total other assets $ 710,491 $ 650,195 

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2018
Acquisitions [Abstract]
Acquisitions	5. ACQUISITIONS The following table summarizes the Company’s cash acquisition capital expenditures:     For the three months For the nine months  ended September 30, ended September 30,  2018 2017 2018 2017   (in thousands)  Acquisitions of towers and related intangible assets (1)(2) $ 110,464 $ 66,338 $ 372,054 $ 124,476  Land buyouts and other assets (3) 8,008 12,488 31,781 36,531  Total cash acquisition capital expenditures $ 118,472 $ 78,826 $ 403,835 $ 161,007  (1) The nine months ended September 30, 2017 excludes $63.3 million of acquisition costs funded through the issuance of 487,963 shares of Class A common stock. (2) The nine months ended September 30, 2017 exclude $21.0 million of acquisitions completed during the second quarter of 2017 which were not funded as of September 30, 2017. (3) In addition, the Company paid $6.7 million and $2.4 million for ground lease extensions and term easements on land underlying the Company’s towers during the three months ended September 30, 2018 and 2017 , respectively, and paid $16.4 million and $10.6 million for ground lease extensions and term easements on land underlying the Company’s towers during the nine months ended September 30, 2018 and 2017 , respectively. The Company recorded these amounts in prepaid rent on its Consolidated Balance Sheets. For acquisitions, the aggregate purchase price is allocated on a relative fair value basis to towers and related intangible assets. The fair values of these net assets acquired are based on management’s estimates and assumptions, as well as other information compiled by management, including valuations that utilize customary valuation procedures and techniques. The fair value estimates are based on available historical information and on future expectations and assumptions deemed reasonable by management at the time. For asset acquisitions, if the actual results differ from the estimates and judgments used in these fair values, the amounts recorded in the consolidated financial statements could be subject to a possible impairment of the intangible assets, or require acceleration of the amortization expense of intangible assets in subsequent periods. For business combinations, the estimates of the fair value of the assets acquired and liabilities assumed at the date of an acquisition are subject to adjustment during the measurement period (up to one year from the particular acquisition date). During the measurement period, the Company will adjust assets and/or liabilities if new information is obtained about facts and circumstances that existed as of the acquisition date that, if known, would have resulted in a revised estimated value of those assets and/or liabilities as of that date. As of September 30, 2018 , there were no purchase price allocations that were preliminary. During the nine months ended September 30, 2018 , the Company acquired 1,237 completed towers and related assets and liabilities consisting of $124.3 million of property and equipment, $262.6 million of intangible assets, and $14.9 million of working capital adjustments. All acquisitions in the quarter ended September 30, 2018 were accounted for as asset acquisitions. Subsequent to September 30, 2018 , the Company acquired 46 towers and related assets for $17.1 million in cash.

Intangible Assets, Net

Intangible Assets, Net	9 Months Ended
	Sep. 30, 2018
Intangible Assets, Net [Abstract]
Intangible Assets, Net	6. INTANGIBLE ASSETS, NET The following table provides the gross and net carrying amounts for each major class of intangible assets:    As of September 30, 2018 As of December 31, 2017  Gross carrying Accumulated Net book Gross carrying Accumulated Net book  amount amortization value amount amortization value   (in thousands)  Current contract intangibles $ 4,349,404 $ (1,846,918) $ 2,502,486 $ 4,355,171 $ (1,673,270) $ 2,681,901  Network location intangibles 1,660,923 (775,454) 885,469 1,617,441 (701,211) 916,230  Intangible assets, net $ 6,010,327 $ (2,622,372) $ 3,387,955 $ 5,972,612 $ (2,374,481) $ 3,598,131  All intangible assets noted above are included in the Company’s site leasing segment. The Company amortizes its intangible assets using the straight-line method over 15 years. Amortization expense relating to the intangible assets above was $100.1 million and $96.8 million for the three months ended September 30, 2018 and 2017 , respectively, and $301.7 million and $286.8 million for the nine months ended September 30, 2018 and 2017 , respectively.

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
	Sep. 30, 2018
Property and Equipment, Net [Abstract]
Property and Equipment, Net	7. PROPERTY AND EQUIPMENT, NET Property and equipment, net (including vehicles held under capital leases) consists of the following:    As of As of  September 30, 2018 December 31, 2017   (in thousands)  Towers and related components $ 4,897,273 $ 4,772,807  Construction-in-process 35,336 34,689  Furniture, equipment, and vehicles 54,880 53,260  Land, buildings, and improvements 656,818 630,370  Total property and equipment 5,644,307 5,491,126  Less: accumulated depreciation (2,856,593) (2,678,780)  Property and equipment, net $ 2,787,714 $ 2,812,346  Construction-in-process represents costs incurred related to towers that are under development and will be used in the Company’s site leasing operations. Depreciation expense was $67.5 million and $65.0 million for the three months ended September 30, 2018 and 2017 , respectively, and $200.6 million and $193.2 million for the nine months ended September 30, 2018 and 2017 , respectively. At September 30, 2018 and December 31, 2017 , non-cash capital expenditures that are included in accrued expenses were $10.5 million and $12.4 million, respectively.

Costs and Estimated Earnings on

Costs and Estimated Earnings on Uncompleted Contracts	9 Months Ended
	Sep. 30, 2018
Costs and Estimated Earnings on Uncompleted Contracts [Abstract]
Costs and Estimated Earnings on Uncompleted Contracts	 8. COSTS AND ESTIMATED EARNINGS ON UNCOMPLETED CONTRACTS The Company’s costs and estimated earnings on uncompleted contracts are comprised of the following:    As of As of  September 30, 2018 December 31, 2017   (in thousands)  Costs incurred on uncompleted contracts $ 33,784 $ 31,404  Estimated earnings 13,662 10,541  Billings to date (30,193) (24,771)  $ 17,253 $ 17,174  These amounts are included in the accompanying Consolidated Balance Sheets under the following captions:    As of As of  September 30, 2018 December 31, 2017   (in thousands)  Costs and estimated earnings in excess of billings on uncompleted contracts $ 17,799 $ 17,437  Billings in excess of costs and estimated earnings on  uncompleted contracts (included in Other current liabilities) (546) (263)  $ 17,253 $ 17,174 At September 30, 2018 and December 31, 2017 , eight customers comprised 95.1% and 87.9% of the costs and estimated earnings in excess of billings on uncompleted contracts, net of billings in excess of costs and estimated earnings, respectively.

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2018
Accrued Expenses [Abstract]
Accrued Expenses	9. ACCRUED EXPENSES The Company’s accrued expenses are comprised of the following:     As of As of  September 30, 2018 December 31, 2017   (in thousands)  Accrued earnouts on business combinations $ 1,875 $ 2,470  Salaries and benefits 11,453 13,506  Real estate and property taxes 9,529 7,125  Non-cash capital expenditures 10,465 12,408  Other 34,807 34,353  Total accrued expenses $ 68,129 $ 69,862  

Debt

Debt	9 Months Ended
	Sep. 30, 2018
Debt [Abstract]
Debt	 10. DEBT The principal values, fair values, and carrying values of debt consist of the following (in thousands):    As of As of  September 30, 2018 December 31, 2017  Maturity Date Principal Balance Fair Value Carrying Value Principal Balance Fair Value Carrying Value  2014 Senior Notes Jul. 15, 2022 $ 750,000 $ 756,563 $ 740,714 $ 750,000 $ 770,625 $ 739,079  2016 Senior Notes Sep. 1, 2024 1,100,000 1,083,500 1,083,071 1,100,000 1,127,500 1,081,262  2017 Senior Notes Oct. 1, 2022 750,000 734,063 742,676 750,000 750,938 741,437  2013-1C Tower Securities Apr. 10, 2018 — — — 425,000 423,853 424,482  2013-2C Tower Securities Apr. 11, 2023 575,000 560,108 569,434 575,000 578,433 568,609  2013-1D Tower Securities Apr. 10, 2018 — — — 330,000 330,145 329,585  2014-1C Tower Securities Oct. 8, 2019 920,000 909,080 917,020 920,000 915,216 914,929  2014-2C Tower Securities Oct. 8, 2024 620,000 599,298 614,099 620,000 620,942 613,461  2015-1C Tower Securities Oct. 8, 2020 500,000 489,080 495,162 500,000 496,840 493,474  2016-1C Tower Securities Jul. 9, 2021 700,000 683,991 694,519 700,000 691,166 693,118  2017-1C Tower Securities Apr. 11, 2022 760,000 734,244 752,530 760,000 751,404 751,076  2018-1C Tower Securities Mar. 9, 2023 640,000 631,789 632,339 — — —  Revolving Credit Facility Apr. 11, 2023 120,000 120,000 120,000 40,000 40,000 40,000  2014 Term Loan Mar. 24, 2021 — — — 1,447,500 1,451,119 1,439,373  2015 Term Loan Jun. 10, 2022 — — — 487,500 488,109 480,801  2018 Term Loan Apr. 11, 2025 2,394,000 2,394,000 2,372,581 — — —  Total debt $ 9,829,000 $ 9,695,716 $ 9,734,145 $ 9,405,000 $ 9,436,290 $ 9,310,686  Less: current maturities of long-term debt (24,000) (20,000)  Total long-term debt, net of current maturities $ 9,710,145 $ 9,290,686  The table below reflects cash and non-cash interest expense amounts recognized by debt instrument for the periods presented:     For the three months ended September 30, For the nine months ended September 30,  2018 2017 2018 2017  Cash Non-cash Cash Non-cash Cash Non-cash Cash Non-cash  Interest Interest Interest Interest Interest Interest Interest Interest   (in thousands)  2014 Senior Notes $ 9,141 $ 191 $ 9,141 $ 182 $ 27,422 $ 567 $ 27,422 $ 540  2016 Senior Notes 13,406 252 13,406 240 40,219 748 40,219 711  2017 Senior Notes 7,500 — — — 22,500 — — —  2012 Tower Securities — — — — — — 5,331 —  2013 Tower Securities 5,396 — 10,804 — 20,267 — 32,413 —  2014 Tower Securities 12,785 — 12,785 — 38,354 — 38,354 —  2015-1C Tower Securities 3,985 — 3,985 — 11,954 — 11,954 —  2016-1C Tower Securities 5,090 — 5,090 — 15,271 — 15,271 —  2017-1C Tower Securities 6,096 — 6,096 — 18,268 — 11,098 —  2018-1C Tower Securities 5,570 — — — 12,502 — — —  Revolving Credit Facility 1,721 — 2,673 — 4,911 — 6,848 —  2014 Term Loan — — 12,964 133 15,550 146 36,291 391  2015 Term Loan — — 4,366 170 5,237 187 12,221 504  2018 Term Loan 25,096 189 — — 46,303 354 — —  Other (69) — 47 — (480) — (7) —  Total $ 95,717 $ 632 $ 81,357 $ 725 $ 278,278 $ 2,002 $ 237,415 $ 2,146  Senior Credit Agreement On April 11, 2018, the Company amended and restated its Senior Credit Agreement to (1) issue a new $2.4 billion Term Loan, (2) increase the total commitments under the Revolving Credit Facility from $1.0 billion to $1.25 billion, (3) extend the maturity date of the Revolving Credit Facility to April 11, 2023 , (4) lower the applicable interest rate margins and commitment fees under the Revolving Credit Facility, and (5) amend certain other terms and conditions under the Senior Credit Agreement. The proceeds from the new Term Loan were used to repay the outstanding balances on the 2014 Term Loan, 2015 Term Loan, and Revolving Credit Facility and for general corporate purposes. This transaction was accounted for as an extinguishment of the 2014 Term Loan and 2015 Term Loan. Revolving Credit Facility under the Senior Credit Agreement As amended, the Revolving Credit Facility consists of a revolving loan under which up to $1.25 billion aggregate principal amount may be borrowed, repaid and redrawn, based upon specific financial ratios and subject to the satisfaction of other customary conditions to borrowing. Amounts borrowed under the Revolving Credit Facility accrue interest, at SBA Senior Finance II’s election, at either (i) the Eurodollar Rate plus a margin that ranges from 112.5 basis points to 175.0 basis points or (ii) the Base Rate plus a margin that ranges from 12.5 basis points to 75.0 basis points, in each case based on the ratio of Consolidated Net Debt to Annualized Borrower EBITDA, calculated in accordance with the Senior Credit Agreement. In addition, SBA Senior Finance II is required to pay a commitment fee of between 0.20% and 0.25% per annum on the amount of unused commitment. If not earlier terminated by SBA Senior Finance II, the Revolving Credit Facility will terminate on, and SBA Senior Finance II will repay all amounts outstanding on or before, April 11, 2023 . The proceeds available under the Revolving Credit Facility may be used for general corporate purposes. During the three and nine months ended September 30, 2018 , the Company borrowed $260.0 million and $805.0 million, respectively, and repaid $225.0 million and $725.0 million, respectively, of the outstanding balance under the Revolving Credit Facility. As of September 30, 2018 , the balance outstanding under the Revolving Credit Facility was $120.0 million accruing interest at 3.88% per annum. In addition, SBA Senior Finance II was required to pay a commitment fee of 0.25% per annum on the amount of the unused commitment. As of September 30, 2018 , SBA Senior Finance II was in compliance with the financial covenants contained in the Senior Credit Agreement. Subsequent to September 30, 2018 , the Company borrowed an additional $95.0 million of the outstanding balance under the Revolving Credit Facility. As of the date of this filing, $ 215.0 million was outstanding under the Revolving Credit Facility. Term Loans under the Senior Credit Agreement 2014 Term Loan The 2014 Term Loan consisted of a senior secured term loan with an initial aggregate principal amount of $1.5 billion that was scheduled to mature on March 24, 2021 . The 2014 Term Loan accrued interest, at SBA Senior Finance II’s election, at either the Base Rate plus 125 basis points (with a zero Base Rate floor) or the Eurodollar Rate plus 225 basis points (with a zero Eurodollar Rate floor). The 2014 Term Loan was originally issued at 99.75% of par value. Principal payments on the 2014 Term Loan commenced on September 30, 2014 and were being made in quarterly installments on the last day of each March, June, September, and December in an amount equal to $3.8 million. The Company incurred financing fees of approximately $14.1 million in relation to this transaction, which were being amortized through the maturity date. During the three months ended March 31, 2018, the Company repaid $3.8 million of principal on the 2014 Term Loan. On April 11, 2018, the Company repaid the remaining $1,443.8 million outstanding principal balance of the 2014 Term Loan with proceeds from the 2018 Term Loan. In connection with the repayment, the Company expensed $5.8 million of net deferred financing fees and $1.7 million of discount related to the debt. 2015 Term Loan The 2015 Term Loan consisted of a senior secured term loan with an initial aggregate principal amount of $500.0 million that was scheduled to mature on June 10, 2022 . The 2015 Term Loan accrued interest, at SBA Senior Finance II’s election at either the Base Rate plus 125 basis points (with a zero Base Rate floor) or the Eurodollar Rate plus 225 basis points (with a zero Eurodollar Rate floor). The 2015 Term Loan was originally issued at 99.0% of par value. Principal payments on the 2015 Term Loan commenced on September 30, 2015 and were being made in quarterly installments on the last day of each March, June, September, and December in an amount equal to $1.3 million. The Company incurred financing fees of approximately $5.5 million in relation to this transaction, which were being amortized through the maturity date. During the three months ended March 31, 2018, the Company repaid $1.3 million of principal on the 2015 Term Loan. On April 11, 2018, the Company repaid the remaining $486.3 million outstanding principal balance of the 2015 Term Loan with proceeds from the 2018 Term Loan. In connection with the repayment, the Company expensed $3.2 million of net deferred financing fees and $3.1 million of discount related to the debt. 2018 Term Loan On April 11, 2018, the Company, through its wholly owned subsidiary, SBA Senior Finance II LLC, obtained a new term loan (the “2018 Term Loan”) under the amended and restated Senior Credit Agreement. The 2018 Term Loan consists of a senior secured term loan with an initial aggregate principal amount of $2.4 billion that matures on April 11, 2025 . The 2018 Term Loan accrues interest, at SBA Senior Finance II’s election at either the Base Rate plus 100 basis points (with a zero Base Rate floor) or the Eurodollar Rate plus 200 basis points (with a zero Eurodollar Rate floor). The 2018 Term Loan was issued at 99.75% of par value. As of September 30, 2018 , the 2018 Term Loan was accruing interest at 4.25% per annum. Principal payments on the 2018 Term Loan commenced on September 30, 2018 and are being made in quarterly installments on the last day of each March, June, September, and December in an amount equal to $6.0 million. The Company incurred financing fees of approximately $16.7 million in relation to this transaction, which are being amortized through the maturity date. The proceeds from the 2018 Term Loan were used (1) to retire the outstanding $1.93 billion in aggregate principal amount of the 2014 Term Loan and 2015 Term Loan, (2) to pay down the existing outstanding balance under the Revolving Credit Facility, and (3) for general corporate purposes. During the three and nine months ended September 30, 2018 , the Company repaid an aggregate of $6.0 million of principal on the 2018 Term Loan. As of September 30, 2018 , the 2018 Term Loan had a principal balance of $2.4 b illion . Secured Tower Revenue Securities 2013 Tower Securities On April 18, 2013, the Company, through a New York common law trust (the “Trust”), issued $425.0 million of 2.240% Secured Tower Revenue Securities Series 2013-1C, which had an anticipated repayment date of April 10, 2018 and a final maturity date of April 9, 2043 (the “2013-1C Tower Securities”), $575.0 million of 3.722% Secured Tower Revenue Securities Series 2013-2C, which have an anticipated repayment date of April 11, 2023 and a final maturity date of April 9, 2048 (the “2013-2C Tower Securities”), and $330.0 million of 3.598% Secured Tower Revenue Securities Series 2013-1D, which had an anticipated repayment date of April 10, 2018 and a final maturity date of April 9, 2043 (the “2013-1D Tower Securities”) (collectively the “2013 Tower Securities”). The aggregate $1.33 billion of 2013 Tower Securities had a blended interest rate of 3.218% per annum, payable monthly. The Company incurred financing fees of $25.5 million in relation to this transaction, which were being amortized through the anticipated repayment date of each of the 2013 Tower Securities. On March 9, 2018, the Company repaid the entire aggregate principal amount of the 2013-1C Tower Securities and 2013-1D Tower Securities in connection with the issuance of the 2018-1C Tower Securities (as defined below). The sole asset of the Trust consists of a non-recourse mortgage loan made in favor of those entities that are borrowers on the mortgage loan (the “Borrowers”). 2014 Tower Securities On October 15, 2014, the Company, through the Trust, issued $920.0 million of 2.898% Secured Tower Revenue Securities Series 2014-1C, which have an anticipated repayment date of October 8, 2019 and a final maturity date of October 11, 2044 (the “2014-1C Tower Securities”) and $620.0 million of 3.869% Secured Tower Revenue Securities Series 2014-2C, which have an anticipated repayment date of October 8, 2024 and a final maturity date of October 8, 2049 (the “2014-2C Tower Securities”) (collectively the “2014 Tower Securities”). The aggregate $1.54 billion of 2014 Tower Securities have a blended interest rate of 3.289% per annum, payable monthly. The Company incurred financing fees of $22.5 million in relation to this transaction, which are being amortized through the anticipated repayment date of each of the 2014 Tower Securities. 2015-1C Tower Securities On October 14, 2015, the Company, through the Trust, issued $500.0 million of Secured Tower Revenue Securities Series 2015-1C, which have an anticipated repayment date of October 8, 2020 and a final maturity date of October 10, 2045 (the “2015-1C Tower Securities”). The fixed interest rate of the 2015-1C Tower Securities is 3.156% per annum, payable monthly. The Company incurred financing fees of $11.2 million in relation to this transaction, which are being amortized through the anticipated repayment date of the 2015-1C Tower Securities. 2016-1C Tower Securities On July 7, 2016, the Company, through the Trust, issued $700.0 million of Secured Tower Revenue Securities Series 2016-1C, which have an anticipated repayment date of July 9, 2021 and a final maturity date of July 10, 2046 (the “2016-1C Tower Securities”). The fixed interest rate of the 2016-1C Tower Securities is 2.877% per annum, payable monthly. The Company incurred financing fees of $9.5 million in relation to this transaction, which are being amortized through the anticipated repayment date of the 2016-1C Tower Securities. 2017-1C Tower Securities On April 17, 2017, the Company, through the Trust, issued $760.0 million of Secured Tower Revenue Securities Series 2017-1C, which have an anticipated repayment date of April 11, 2022 and a final maturity date of April 9, 2047 (the “2017-1C Tower Securities”). The fixed interest rate on the 2017-1C Tower Securities is 3.168% per annum, payable monthly. Net proceeds from this offering were used to prepay the entire $610.0 million aggregate principal amount, as well as accrued and unpaid interest, of the 2012-1C Tower Securities and for general corporate purposes. The Company incurred financing fees of $10.2 million in relation to this transaction, which are being amortized through the anticipated repayment date of the 2017-1C Tower Securities.  In addition, to satisfy certain risk retention requirements of Regulation RR promulgated under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), SBA Guarantor, LLC, a wholly owned subsidiary, purchased $40.0 million of Secured Tower Revenue Securities Series 2017-1R issued by the Trust, which have an anticipated repayment date of April 11, 2022 and a final maturity date of April 9, 2047 (the “2017-1R Tower Securities”). The fixed interest rate on the 2017-1R Tower Securities is 4.459% per annum, payable monthly. Principal and interest payments made on the 2017-1R Tower Securities eliminate in consolidation. 2018-1C Tower Securities On March 9, 2018, the Company, through the Trust, issued $640.0 million of Secured Tower Revenue Securities Series 2018-1C, which have an anticipated repayment date of March 9, 2023 and a final maturity date of March 9, 2048 (the “2018-1C Tower Securities”). The fixed interest rate on the 2018-1C Tower Securities is 3.448% per annum, payable monthly. Net proceeds from this offering, in combination with borrowings under the Revolving Credit Facility, were used to repay the entire aggregate principal amount of the 2013-1C Tower Securities ( $425.0 million) and 2013-1D Tower Securities ( $330.0 million), as well as accrued and unpaid interest. The Company incurred financing fees of $8.5 million in relation to this transaction, which are being amortized through the anticipated repayment date of the 2018-1C Tower Securities. In addition, to satisfy certain risk retention requirements of Regulation RR promulgated under the Exchange Act, SBA Guarantor, LLC, a wholly owned subsidiary, purchased $33.7 million of Secured Tower Revenue Securities Series 2018-1R issued by the Trust. These securities have an anticipated repayment date of March 9, 2023 and a final maturity date of March 9, 2048 (the “2018-1R Tower Securities”). The fixed interest rate on the 2018-1R Tower Securities is 4.949% per annum, payable monthly. Principal and interest payments made on the 2018-1R Tower Securities eliminate in consolidation. In connection with the issuance of the 2018-1C Tower Securities, the non-recourse mortgage loan was increased by $673.7 million (but decreased by a net of $81.3 million after giving effect to prepayment of the loan components relating to the 2013-1C Tower Securities and 2013-1D Tower Securities). The new loan, after eliminating the risk retention securities, accrues interest at the same rate as the 2018-1C Tower Securities and is subject to all other material terms of the existing mortgage loan, including collateral and interest rate after the anticipated repayment date. Debt Covenants As of September 30, 2018 , the Borrowers met the debt service coverage ratio required by the mortgage loan agreement and were in compliance with all other covenants as set forth in the agreement. Senior Notes 2014 Senior Notes On July 1, 2014, the Company issued $750.0 million of unsecured senior notes due July 15, 2022 (the “2014 Senior Notes”). The 2014 Senior Notes accrue interest at a rate of 4.875% per annum and were issued at 99.178% of par value. Interest on the 2014 Senior Notes is due semi-annually on January 15 and July 15 of each year. The Company incurred financing fees of $11.6 million in relation to this transaction, which are being amortized through the maturity date. The 2014 Senior Notes are subject to redemption in whole or in part at the redemption prices set forth in the indenture agreement plus accrued and unpaid interest. The Company may redeem the 2014 Senior Notes during the twelve-month period beginning on the following dates at the following redemption prices: July 15, 2018 at 102.438% , July 15, 2019 at 101.219% , or July 15, 2020 until maturity at 100.000% , of the principal amount of the 2014 Senior Notes to be redeemed on the redemption date plus accrued and unpaid interest. 2016 Senior Notes On August 15, 2016, the Company issued $1.1 billion of unsecured senior notes due September 1, 2024 (the “2016 Senior Notes”). The 2016 Senior Notes accrue interest at a rate of 4.875% per annum and were issued at 99.178% of par value. Interest on the 2016 Senior Notes is due semi-annually on March 1 and September 1 of each year, beginning on March 1, 2017. The Company incurred financing fees of $12.8 million in relation to this transaction, which are being amortized through the maturity date. Net proceeds from this offering and cash on hand were used to redeem $800.0 million, the aggregate principal amount outstanding, of Telecommunications’ 5.75% Senior Notes and $250.0 million of the Company’s 5.625% Senior Notes and pay the associated call premiums. The 2016 Senior Notes are subject to redemption in whole or in part on or after September 1, 2019 at the redemption prices set forth in the indenture agreement plus accrued and unpaid interest. Prior to September 1, 2019, the Company may, at its option, redeem up to 35% of the aggregate principal amount of the 2016 Senior Notes originally issued at a redemption price of 104.875% of the principal amount of the 2016 Senior Notes to be redeemed on the redemption date plus accrued and unpaid interest with the net proceeds of certain equity offerings. The Company may redeem the 2016 Senior Notes during the twelve-month period beginning on the following dates at the following redemption prices: September 1, 2019 at 103.656% , September 1, 2020 at 102.438% , September 1, 2021 at 101.219% , or September 1, 2022 until maturity at 100.000% , of the principal amount of the 2016 Senior Notes to be redeemed on the redemption date plus accrued and unpaid interest. 2017 Senior Notes On October 13, 2017, the Company issued $750.0 million of unsecured senior notes due October 1, 2022 (the “2017 Senior Notes”). The 2017 Senior Notes accrue interest at a rate of 4.0% per annum. Interest on the 2017 Senior Notes is due semi-annually on April 1 and October 1 of each year, beginning on April 1, 2018. The Company incurred financing fees of $8.9 million in relation to this transaction, which are being amortized through the maturity date. Net proceeds from this offering were used to repay $460.0 million outstanding under the Revolving Credit Facility and for general corporate purposes. The 2017 Senior Notes are subject to redemption in whole or in part on or after October 1, 2019 at the redemption prices set forth in the indenture agreement plus accrued and unpaid interest. Prior to October 1, 2020, the Company may, at its option, redeem up to 35% of the aggregate principal amount of the 2017 Senior Notes originally issued at a redemption price of 104.000% of the principal amount of the 2017 Senior Notes to be redeemed on the redemption date plus accrued and unpaid interest with the net proceeds of certain equity offerings. The Company may redeem the 2017 Senior Notes during the twelve-month period beginning on the following dates at the following redemption prices: October 1, 2019 at 102.000% , October 1, 2020 at 101.000% , or October 1, 2021 until maturity at 100.000% , of the principal amount of the 2017 Senior Notes to be redeemed on the redemption date plus accrued and unpaid interest.

Shareholders' Equity

Shareholders' Equity	9 Months Ended
	Sep. 30, 2018
Shareholders' Equity [Abstract]
Shareholders' Equity	11. SHAREHOLDERS’ EQUITY Common Stock Equivalents The Company has potential common stock equivalents (see Note 12) related to its outstanding stock options and restricted stock units. These potential common stock equivalents were considered in the Company’s diluted earnings per share calculation (see Note 15). Stock Repurchases On February 16, 2018, the Company’s Board of Directors authorized a $1.0 billion stock repurchase plan, replacing the prior plan authorized on January 12, 2017 which had a remaining authorization of $150.0 million. This new plan authorizes the Company to purchase, from time to time, up to $1.0 billion of the outstanding Class A common stock through open market repurchases in compliance with Rule 10b-18 under the Exchange Act and/or in privately negotiated transactions at management’s discretion based on market and business conditions, applicable legal requirements and other factors. Shares repurchased will be retired. The plan has no time deadline and will continue until otherwise modified or terminated by the Company’s Board of Directors at any time in its sole discretion. During the three months ended September 30, 2018 , the Company repurchased 0.7 million shares of its Class A common stock under this plan for $108.0 million, at an average price per share of $155.16 . During the nine months ended September 30, 2018 , the Company repurchased 2.8 million shares of its Class A common stock under this plan for $453.5 million, at an average price per share of $161.23 . Shares repurchased were retired. Subsequent to September 30, 2018 , the Company repurchased 0.9 million shares of its Class A common stock for $142.0 million, at an average price per share of $151.55 . Shares repurchased were retired. As of the date of this filing, the Company had $404.5 million of authorization remaining under the current stock repurchase plan.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2018
Stock-Based Compensation [Abstract]
Stock-Based Compensation	 12. STOCK-BASED COMPENSATION Stock Options The Company records compensation expense for employee stock options based on the estimated fair value of the options on the date of grant using the Black-Scholes option-pricing model with the assumptions included in the table below. The Company uses a combination of historical data and historical volatility to establish the expected volatility, as well as to estimate the expected option life. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for the estimated life of the option. The following assumptions were used to estimate the fair value of options granted using the Black-Scholes option-pricing model:    For the nine months ended  September 30,  2018 2017   Risk free interest rate 2.57% - 2.87% 1.70% - 1.97%  Dividend yield 0.7% 0.0%  Expected volatility 22% 20%  Expected lives 4.6 years 4.6 years  The following table summarizes the Company’s activities with respect to its stock option plans for the nine months ended September 30, 2018 as follows (dollars and shares in thousands, except for per share data):    Weighted- Weighted-Average  Average Remaining  Number Exercise Price Contractual Aggregate  of Shares Per Share Life (in years) Intrinsic Value  Outstanding at December 31, 2017 4,842 $ 100.12  Granted 937 $ 156.54  Exercised (548) $ 81.99  Forfeited/canceled (38) $ 123.91  Outstanding at September 30, 2018 5,193 $ 112.05 4.3 $ 252,235  Exercisable at September 30, 2018 2,538 $ 97.34 3.1 $ 160,627  Unvested at September 30, 2018 2,655 $ 126.11 5.4 $ 91,608 The weighted-average per share fair value of options granted during the nine months ended September 30, 2018 was $33.00 . The total intrinsic value for options exercised during the nine months ended September 30, 2018 was $44.2 million. Restricted Stock Units The following table summarizes the Company’s restricted stock unit activity for the nine months ended September 30, 2018 :    Weighted-Average  Number of Grant Date Fair  Shares Value per Share  (in thousands)  Outstanding at December 31, 2017 328 $ 110.20  Granted 137 $ 156.61  Vested (129) $ 110.94  Forfeited/canceled (11) $ 134.37  Outstanding at September 30, 2018 325 $ 128.73

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Taxes [Abstract]
Income Taxes	13. INCOME TAXES The primary reasons for the difference between the Company’s effective tax rate and the U.S. statutory rate are the Company’s REIT election and the Company’s full valuation allowance on the net deferred tax assets of the U.S. taxable REIT subsidiary (“TRS”). The Company has concluded that it is not more likely than not that its deferred tax assets will be realized and has recorded a full valuation allowance. A foreign tax provision is recognized because certain foreign subsidiaries of the Company have profitable operations or are in a net deferred tax liability position. The Company elected to be taxed as a REIT commencing with its taxable year ended December 31, 2016. As a REIT, the Company generally will be entitled to a deduction for dividends that it pays, and therefore, not subject to U.S. federal corporate income tax on that portion of its net income that it distributes to its shareholders. As a REIT, the Company will continue to pay U.S. federal income tax on earnings, if any, from assets and operations held through its TRSs. These assets and operations currently consist primarily of the Company’s site development services and its international operations. The Company’s international operations would continue to be subject, as applicable, to foreign taxes in the jurisdictions in which those operations are located. The Company may also be subject to a variety of taxes, including payroll taxes and state, local, and foreign income, property, and other taxes on its assets and operations. The Company’s determination as to the timing and amount of future dividend distributions will be based on a number of factors, including REIT distribution requirements, its existing federal net operating losses (“NOLs”) of approximately $1.0 billion as of December 31, 2017, the Company’s financial condition, earnings, debt covenants, and other possible uses of such funds. The Company may use these NOLs to offset its REIT taxable income, and thus any required distributions to shareholders may be reduced or eliminated until such time as the NOLs have been fully utilized. The Tax Cuts and Jobs Act (the “Tax Act”) was enacted on December 22, 2017. The Tax Act reduces the U.S. federal corporate income tax rate from 35% to 21% , requires companies to pay a one-time transition tax on earnings of certain foreign subsidiaries that were previously tax deferred and creates new taxes on certain foreign sourced earnings. The Company is applying the guidance in Staff Accounting Bulletin No. 118 when accounting for the enactment-date effects of the Tax Act. As of September 30, 2018, the Company has not recognized any adjustments to the provisional amounts recorded at December 31, 2017. As additional guidance becomes available related to the Tax Act, the Company will continue to refine its calculations. These estimates may also be affected as the Company gains a more thorough understanding of the Tax Act. These changes may be material to income tax expense. The global intangible low-taxed income (“GILTI”) provisions of the Tax Act impose a tax on the income of certain foreign subsidiaries in excess of a specified return on tangible assets used by the foreign companies. FASB Staff Q&A, Topic 740, No. 5, Accounting for Global Intangible Low-Taxed Income, states that an entity can make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years or provide for the tax expense related to GILTI in the year the tax is incurred. Given the complexity of the GILTI provisions, the Company is still evaluating the effects of the GILTI provisions and has not yet determined the new accounting policy it intends to elect. At September 30, 2018, because the Company is still evaluating the GILTI provisions and the analysis of future taxable income subject to GILTI, the Company has included GILTI related to current-year operations only and have not provided additional GILTI on deferred items. During the quarter ended September 30, 2018 the Company updated the provisional amounts for the annualized GILTI deemed dividend, which res ulted in a reduction from $35.7 million to $12.9 million . Also, recently released IRS guidance has clarified that GILTI and other deemed dividends are considered qualifying in come for REIT testing purposes.

Segment Data

Segment Data	9 Months Ended
	Sep. 30, 2018
Segment Data [Abstract]
Segment Data	14. SEGMENT DATA The Company operates principally in two business segments: site leasing and site development. The Company’s site leasing business includes two reportable segments, domestic site leasing and international site leasing. The Company’s business segments are strategic business units that offer different services. They are managed separately based on the fundamental differences in their operations. The site leasing segment includes results of the managed and sublease businesses. The site development segment includes the results of both consulting and construction related activities. The Company’s Chief Operating Decision Maker utilizes segment operating profit and operating income as his two measures of segment profit in assessing performance and allocating resources at the reportable segment level. The Company has applied the aggregation criteria to operations within the international site leasing segment on a basis that is consistent with management’s review of information and performance evaluations of the individual markets in this region. Revenues, cost of revenues (exclusive of depreciation, accretion and amortization), capital expenditures (including assets acquired through the issuance of shares of the Company’s Class A common stock) and identifiable assets pertaining to the segments in which the Company continues to operate are presented below.     Domestic Site Int'l Site Site Not Identified  Leasing Leasing Development by Segment Total   For the three months ended September 30, 2018 (in thousands)  Revenues $ 353,502 $ 81,758 $ 31,961 $ — $ 467,221  Cost of revenues (2) 66,862 25,432 24,447 — 116,741  Operating profit 286,640 56,326 7,514 — 350,480  Selling, general, and administrative 17,763 6,734 3,934 6,477 34,908  Acquisition related adjustments and expenses 1,887 1,108 — — 2,995  Asset impairment and decommission costs 2,801 4,067 — — 6,868  Depreciation, amortization and accretion 129,246 36,310 646 1,501 167,703  Operating income (loss) 134,943 8,107 2,934 (7,978) 138,006  Other expense (principally interest expense  and other income (expense)) (123,841) (123,841)  Income before income taxes 14,165  Cash capital expenditures (3) 33,794 120,176 425 666 155,061   For the three months ended September 30, 2017  Revenues $ 328,395 $ 80,143 $ 25,407 $ — $ 433,945  Cost of revenues (2) 65,226 25,125 21,117 — 111,468  Operating profit 263,169 55,018 4,290 — 322,477  Selling, general, and administrative 16,945 6,658 3,826 5,130 32,559  Acquisition related adjustments and expenses 962 621 — — 1,583  Asset impairment and decommission costs 7,898 1,554 (35) — 9,417  Depreciation, amortization and accretion 125,142 34,548 605 1,612 161,907  Operating income (loss) 112,222 11,637 (106) (6,742) 117,011  Other expense (principally interest expense  and other income (expense)) (64,472) (64,472)  Income before income taxes 52,539  Cash capital expenditures (3) 57,352 57,507 372 724 115,955      Not  Domestic Site Int'l Site Site Identified by  Leasing Leasing Development Segment Total   For the nine months ended September 30, 2018 (in thousands)  Revenues $ 1,041,892 $ 253,794 $ 86,160 $ — $ 1,381,846  Cost of revenues (2) 199,633 79,167 67,693 — 346,493  Operating profit 842,259 174,627 18,467 — 1,035,353  Selling, general, and administrative 55,047 20,242 11,943 19,669 106,901  Acquisition related adjustments and expenses 5,242 3,929 — — 9,171  Asset impairment and decommission costs 15,971 6,475 332 — 22,778  Depreciation, amortization and accretion 382,490 113,550 1,936 4,683 502,659  Operating income (loss) 383,509 30,431 4,256 (24,352) 393,844  Other expense (principally interest expense  and other income (expense)) (415,191) (415,191)  Loss before income taxes (21,347)  Cash capital expenditures (3) 287,711 218,739 1,345 2,148 509,943   For the nine months ended September 30, 2017  Revenues $ 974,850 $ 234,239 $ 75,513 $ — $ 1,284,602  Cost of revenues (2) 195,903 73,167 62,713 — 331,783  Operating profit 778,947 161,072 12,800 — 952,819  Selling, general, and administrative 53,147 19,007 11,495 16,528 100,177  Acquisition related adjustments and expenses 4,300 2,557 — — 6,857  Asset impairment and decommission costs 22,746 2,956 206 — 25,908  Depreciation, amortization and accretion 373,262 100,388 1,968 4,839 480,457  Operating income (loss) 325,492 36,164 (869) (21,367) 339,420  Other expense (principally interest expense  and other income (expense)) (233,259) (233,259)  Income before income taxes 106,161  Cash capital expenditures (3) 160,814 103,609 692 2,456 267,571       Domestic Site Int'l Site Site Not Identified  Leasing Leasing Development by Segment (1) Total   Assets (in thousands)  As of September 30, 2018 $ 5,093,302 $ 1,988,380 $ 51,494 $ 80,647 $ 7,213,823  As of December 31, 2017 $ 5,171,190 $ 2,028,479 $ 49,487 $ 71,049 $ 7,320,205  (1) Assets not identified by segment consist primarily of general corporate assets. (2) Excludes depreciation, amortization, and accretion. (3) Includes cash paid for capital expenditures and acquisitions and vehicle capital lease additions. Other than Brazil, no foreign country represented a material amount of the Company’s total revenues in any of the periods presented. Site leasing revenue in Brazil was $167.1 million and $162.3 million for the nine months ended September 30, 2018 and 2017 , respectively. Total long-lived assets in Brazil were $1,003.6 million and $1,278.9 million as of September 30, 2018 and December 31, 2017 , respectively.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share	15. EARNINGS PER SHARE Basic earnings per share was computed by dividing net income attributable to common shareholders by the weighted-average number of shares of Common Stock outstanding for each respective period. Diluted earnings per share was calculated by dividing net income attributable to common shareholders by the weighted-average number of shares of Common Stock outstanding adjusted for any dilutive Common Stock equivalents, including unvested restricted stock and shares issuable upon exercise of stock options as determined under the “If-Converted” method and also Common Stock warrants as determined under the “Treasury Stock” method. The following table sets forth basic and diluted net income per common share for the three and nine months ended September 30, 2018 and 2017 (in thousands, except per share data):     For the three months For the nine months  ended September 30, ended September 30,  2018 2017 2018 2017  Numerator:  Net income (loss) $ 16,144 $ 49,161 $ (9,702) $ 95,994  Denominator:  Basic weighted-average shares outstanding 114,597 119,746 115,378 120,745  Dilutive impact of stock options and restricted shares 1,517 1,280 — 982  Diluted weighted-average shares outstanding 116,114 121,026 115,378 121,727  Net income (loss) per common share:  Basic $ 0.14 $ 0.41 $ (0.08) $ 0.80  Diluted $ 0.14 $ 0.41 $ (0.08) $ 0.79  For the three months ended September 30, 2018 , the diluted weighted average number of common shares outstanding excluded an additional 0.9 million shares issuable upon exercise of the Company’s stock options because the impact would be anti-dilutive.  For the nine months ended September 30, 2018 , all potential common stock equivalents, including 5.2 million shares of stock options outstanding and 0.3 million shares of restricted stock units outstanding, were excluded as the effect would be anti-dilutive.  For the three and nine months ended September 30, 2017 , the diluted weighted average number of common shares outstanding excluded an additional 11,674 and 1.8 million shares, respectively, issuable upon exercise of the Company’s stock options because the impact would be anti-dilutive.

Basis of Presentation (Policy)

Basis of Presentation (Policy)	9 Months Ended
	Sep. 30, 2018
Basis of Presentation [Abstract]
Basis of Presentation	The accompanying consolidated financial statements should be read in conjunction with the Annual Report on Form 10-K for the fiscal year ended December 31, 2017 for SBA Communications Corporation and its subsidiaries (the “Company”). These financial statements have been prepared in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X and, therefore, omit or condense certain footnotes and other information normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States. In the opinion of the Company’s management, all adjustments (consisting of normal recurring accruals) considered necessary for fair financial statement presentation have been made. The results of operations for an interim period may not give a true indication of the results for the year. Certain reclassifications have been made to prior year amounts or balances to conform to the presentation adopted in the current year. The preparation of financial statements requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. While the Company believes that such estimates are fair when considered in conjunction with the consolidated financial statements and accompanying notes, the actual amounts, when known, may vary from these estimates.
Revenue Recognition and Accounts Receivable	Revenue Recognition and Accounts Receivable Revenue from site leasing is recognized on a straight-line basis over the current term of the related lease agreements, which are generally five to ten years. Receivables recorded related to the straight-line impact of site leases are reflected in other assets on the Consolidated Balance Sheets. Rental amounts received in advance are recorded as deferred revenue on the Consolidated Balance Sheets. Revenues from site leasing represent 94% of the Company’s total revenues. Site development projects in which the Company performs consulting services include contracts on a fixed price basis that are billed at contractual rates. Revenue is recognized over time based on milestones achieved, which are determined based on costs incurred. Amounts billed in advance (collected or uncollected) are recorded as deferred revenue on the Consolidated Balance Sheets. Revenue from construction projects is recognized over time, determined by the percentage of cost incurred to date compared to management’s estimated total cost for each contract. This method is used because management considers total cost to be the best available measure of progress on the contracts. These amounts are based on estimates, and the uncertainty inherent in the estimates initially is reduced as work on the contracts nears completion. Refer to Note 8 for further detail of costs and estimated earnings in excess of billings on uncompleted contracts. Provisions for estimated losses on uncompleted contracts are made in the period in which such losses are determined to be probable. The site development segment represents approximately 6% of the Company’s total revenues. The Company accounts for site development revenue in accordance with ASC 606, Revenue from Contracts with Customers, which was adopted on January 1, 2018 by applying the modified retrospective transition method. Payment terms do not result in any significant financing arrangements. Furthermore, these contracts do not typically include variable consideration; therefore, the transaction price that is recognized over time is generally the amount of the total contract. The cumulative effect of initially applying the new revenue standard had no impact on the Company’s financial results. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. The adoption of the new standard will have no impact to net income on an ongoing basis. The accounts receivable balance was $89.3 million and $90.7 million as of September 30, 2018 and December 31, 2017 , respectively, of which $23.2 million and $20.8 million related to the site development segment as of September 30, 2018 and December 31, 2017 , respectively. The Company performs periodic credit evaluations of its customers. In addition, the Company monitors collections and payments from its customers and maintains a provision for estimated credit losses based upon historical experience, specific customer collection issues identified, and past due balances as determined based on contractual terms. Interest is charged on outstanding receivables from customers on a case by case basis in accordance with the terms of the respective contracts or agreements with those customers. Amounts determined to be uncollectible are written off against the allowance for doubtful accounts in the period in which uncollectibility is determined to be probable. Refer to Note 14 for further detail of the site development segment.
Foreign Currency Translation	Foreign Currency Translation All assets and liabilities of foreign subsidiaries that do not utilize the U.S. dollar as its functional currency are translated at period-end rates of exchange, while revenues and expenses are translated at monthly average rates of exchange prevailing during the period. Unrealized remeasurement gains and losses are reported as foreign currency translation adjustments through Accumulated Other Comprehensive Loss in the accompanying Consolidated Statement of Shareholders’ Deficit. For foreign subsidiaries where the U.S. dollar is the functional currency, monetary assets and liabilities of such subsidiaries, which are not denominated in U.S. dollars, are remeasured at exchange rates in effect at the balance sheet date, and revenues and expenses are remeasured at monthly average rates prevailing during the year. Unrealized translation gains and losses are reported as other income (expense), net in the Consolidated Statement of Operations. The Argentinean economy was deemed to be highly inflationary as of the second quarter of 2018 and, as a result, the Company adopted highly inflationary accounting as of July 1, 2018 for its subsidiary in Argentina. Under highly inflationary accounting, the functional currency of its subsidiary in Argentina became the U.S. Dollar. All monetary and non-monetary assets and liabilities were remeasured at the U.S. Dollar to Argentinean Peso exchange rate of 1 to 28.9 as of June 30, 2018. These amounts became the new basis for those assets and liabilities as of July 1, 2018. Non-monetary assets and liabilities, as well as the corresponding income statement activities such as depreciation, amortization and equity, will continue to be measured at the historical exchange rate. This change did not have a material impact on the Company’s financial statements as Argentina’s assets and revenue are each less than 1% of consolidated assets and revenue , respectively.
Intercompany Loans Subject to Remeasurement	Intercompany Loans Subject to Remeasurement The Company has two wholly owned subsidiaries, Brazil Shareholder I, LLC, a Florida limited liability company, and SBA Torres Brasil, Limitada, a limited liability company existing under the laws of the Republic of Brazil, which have entered into intercompany loan agreements pursuant to which the entities may from time to time agree to lend/borrow amounts under the terms of each agreement. The first agreement entered into in November 2014 was for $750.0 million and was created to fund the acquisition of 1,641 towers in Brazil. The second agreement entered into in December 2017 was for $500.0 million and was created to fund the acquisition of 941 towers in Brazil. In accordance with Accounting Standards Codification (ASC) 830, the Company remeasures foreign denominated intercompany loans with the corresponding change in the balance being recorded in Other income (expense), net in the Consolidated Statement of Operations as settlement is anticipated or planned in the foreseeable future. The Company recorded a $25.9 million loss and an $18.4 million gain on the remeasurement of intercompany loans for the three months ended September 30, 2018 and 2017 , respectively, and a $113.1 million loss and an $11.6 million gain on the remeasurement of intercompany loans for the nine months ended September 30, 2018 and 2017 , respectively, due to changes in foreign exchange rates. As of September 30, 2018 , the aggregate amount outstanding under the two intercompany loan agreements with the Company’s Brazilian subsidiary was $536.9 million.
Recent Accounting Pronouncements Not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU 2016-02, Leases. The standard requires lessees to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments for all leases with a term greater than 12 months. The accounting for lessors remains largely unchanged from existing guidance. This standard is effective for annual and interim periods beginning after December 15, 2018. Early adoption is permitted; however, the Company does not currently plan to early adopt. The Company has established a cross functional project plan and is in the process of testing key system functionality developed in order to account for the new standard. The Company expects this guidance to have a material impact on its consolidated balance sheet due to the recognition of right-of-use assets and lease liabilities for its ground leases. The Company does not expect adoption to have a significant impact on its lease classification, a material impact on its consolidated statement of operations, or a notable impact on its liquidity. Additionally, the sta ndard will have no impact on the Company’s debt-covenant compliance under its current agreements. In July 2018, the FASB issued additional guidance on the accounting for leases. The guidance provides companies with another transition method that allows entities to recognize a cumulative-effect adjustment to the opening balance of retained earnings as of the date of adoption. Under this method, previously presented years’ financial positions and results would not be adjusted. The Company expects it will adopt this alternative transition method. The new guidance also provides lessors with a practical expedient, by class of underlying asset, to not separate non-lease components from the associated lease component if (1) the non-lease components would otherwise be accounted for under the new revenue recognition standard, (2) both the timing and pattern of transfer are the same for the non-lease components and associated lease component, and (3) if accounted for separately, the lease component would be classified as an operating lease. The Company is assessing the use of this practical expedient in its accounting for leases.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Measurements [Abstract]
Summary of Asset Impairment and Decommission Costs	     For the three months For the nine months  ended September 30, ended September 30,  2018 2017 2018 2017   Asset impairment (1) $ 2,909 $ 4,128 $ 13,291 $ 10,162  Write-off of carrying value of decommissioned towers 3,561 4,496 7,932 12,143  Other (including third party decommission costs) 398 793 1,555 3,603  Total asset impairment and decommission costs $ 6,868 $ 9,417 $ 22,778 $ 25,908  (1) Represents impairment charges resulting from the Company’s regular analysis of whether the future cash flows from certain towers are adequate to recover the carrying value of the investment in those towers.

Restricted Cash (Tables)

Restricted Cash (Tables)	9 Months Ended
	Sep. 30, 2018
Restricted Cash [Abstract]
Schedule of Cash, Cash Equivalents and Restricted Cash	   As of As of  September 30, 2018 December 31, 2017 Included on Balance Sheet   (in thousands)  Cash and cash equivalents $ 136,221 $ 68,783  Securitization escrow accounts 24,504 32,699 Restricted cash - current asset  Payment and performance bonds 196 225 Restricted cash - current asset  Surety bonds and workers compensation 2,403 2,588 Other assets - noncurrent  Total cash, cash equivalents, and restricted cash $ 163,324 $ 104,295 

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets and Other Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Prepaid Expenses and Other Current Assets and Other Assets [Abstract]
Schedule of Prepaid Expense and Other Current Assets	   As of As of  September 30, 2018 December 31, 2017   (in thousands)  Prepaid ground rent $ 31,323 $ 32,505  Loan receivables 10,877 948  Other 17,441 16,263  Total prepaid expenses and other current assets $ 59,641 $ 49,716 
Schedule of Other Assets	   As of As of  September 30, 2018 December 31, 2017   (in thousands)  Prepaid ground rent $ 252,506 $ 220,493  Straight-line rent receivable 317,422 313,650  Loan receivables 45,300 52,383  Deferred lease costs, net 26,682 27,703  Deferred tax asset - long term 28,130 1,670  Other 40,451 34,296  Total other assets $ 710,491 $ 650,195 

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2018
Acquisitions [Abstract]
Schedule of Acquisition Capital Expenditures	    For the three months For the nine months  ended September 30, ended September 30,  2018 2017 2018 2017   (in thousands)  Acquisitions of towers and related intangible assets (1)(2) $ 110,464 $ 66,338 $ 372,054 $ 124,476  Land buyouts and other assets (3) 8,008 12,488 31,781 36,531  Total cash acquisition capital expenditures $ 118,472 $ 78,826 $ 403,835 $ 161,007  (1) The nine months ended September 30, 2017 excludes $63.3 million of acquisition costs funded through the issuance of 487,963 shares of Class A common stock. (2) The nine months ended September 30, 2017 exclude $21.0 million of acquisitions completed during the second quarter of 2017 which were not funded as of September 30, 2017. (3) In addition, the Company paid $6.7 million and $2.4 million for ground lease extensions and term easements on land underlying the Company’s towers during the three months ended September 30, 2018 and 2017 , respectively, and paid $16.4 million and $10.6 million for ground lease extensions and term easements on land underlying the Company’s towers during the nine months ended September 30, 2018 and 2017 , respectively. The Company recorded these amounts in prepaid rent on its Consolidated Balance Sheets.

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	9 Months Ended
	Sep. 30, 2018
Intangible Assets, Net [Abstract]
Gross and Net Carrying Amounts for each Major Class of Intangible Assets	   As of September 30, 2018 As of December 31, 2017  Gross carrying Accumulated Net book Gross carrying Accumulated Net book  amount amortization value amount amortization value   (in thousands)  Current contract intangibles $ 4,349,404 $ (1,846,918) $ 2,502,486 $ 4,355,171 $ (1,673,270) $ 2,681,901  Network location intangibles 1,660,923 (775,454) 885,469 1,617,441 (701,211) 916,230  Intangible assets, net $ 6,010,327 $ (2,622,372) $ 3,387,955 $ 5,972,612 $ (2,374,481) $ 3,598,131 

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
	Sep. 30, 2018
Property and Equipment, Net [Abstract]
Property and Equipment, Net (Including Assets Held Under Capital Leases)	   As of As of  September 30, 2018 December 31, 2017   (in thousands)  Towers and related components $ 4,897,273 $ 4,772,807  Construction-in-process 35,336 34,689  Furniture, equipment, and vehicles 54,880 53,260  Land, buildings, and improvements 656,818 630,370  Total property and equipment 5,644,307 5,491,126  Less: accumulated depreciation (2,856,593) (2,678,780)  Property and equipment, net $ 2,787,714 $ 2,812,346 

Costs and Estimated Earnings _2

Costs and Estimated Earnings on Uncompleted Contracts (Tables)	9 Months Ended
	Sep. 30, 2018
Costs and Estimated Earnings on Uncompleted Contracts [Abstract]
Summary of Costs and Estimated Earnings on Uncompleted Contracts	   As of As of  September 30, 2018 December 31, 2017   (in thousands)  Costs incurred on uncompleted contracts $ 33,784 $ 31,404  Estimated earnings 13,662 10,541  Billings to date (30,193) (24,771)  $ 17,253 $ 17,174 
Costs and Estimated Earnings on Uncompleted Contracts Accompanying Consolidated Balance Sheets	   As of As of  September 30, 2018 December 31, 2017   (in thousands)  Costs and estimated earnings in excess of billings on uncompleted contracts $ 17,799 $ 17,437  Billings in excess of costs and estimated earnings on  uncompleted contracts (included in Other current liabilities) (546) (263)  $ 17,253 $ 17,174 

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2018
Accrued Expenses [Abstract]
Schedule of Accrued Expenses	   As of As of  September 30, 2018 December 31, 2017   (in thousands)  Accrued earnouts on business combinations $ 1,875 $ 2,470  Salaries and benefits 11,453 13,506  Real estate and property taxes 9,529 7,125  Non-cash capital expenditures 10,465 12,408  Other 34,807 34,353  Total accrued expenses $ 68,129 $ 69,862 

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2018
Debt [Abstract]
Schedule of Principal Values, Fair Values, and Carrying Values of Debt	   As of As of  September 30, 2018 December 31, 2017  Maturity Date Principal Balance Fair Value Carrying Value Principal Balance Fair Value Carrying Value  2014 Senior Notes Jul. 15, 2022 $ 750,000 $ 756,563 $ 740,714 $ 750,000 $ 770,625 $ 739,079  2016 Senior Notes Sep. 1, 2024 1,100,000 1,083,500 1,083,071 1,100,000 1,127,500 1,081,262  2017 Senior Notes Oct. 1, 2022 750,000 734,063 742,676 750,000 750,938 741,437  2013-1C Tower Securities Apr. 10, 2018 — — — 425,000 423,853 424,482  2013-2C Tower Securities Apr. 11, 2023 575,000 560,108 569,434 575,000 578,433 568,609  2013-1D Tower Securities Apr. 10, 2018 — — — 330,000 330,145 329,585  2014-1C Tower Securities Oct. 8, 2019 920,000 909,080 917,020 920,000 915,216 914,929  2014-2C Tower Securities Oct. 8, 2024 620,000 599,298 614,099 620,000 620,942 613,461  2015-1C Tower Securities Oct. 8, 2020 500,000 489,080 495,162 500,000 496,840 493,474  2016-1C Tower Securities Jul. 9, 2021 700,000 683,991 694,519 700,000 691,166 693,118  2017-1C Tower Securities Apr. 11, 2022 760,000 734,244 752,530 760,000 751,404 751,076  2018-1C Tower Securities Mar. 9, 2023 640,000 631,789 632,339 — — —  Revolving Credit Facility Apr. 11, 2023 120,000 120,000 120,000 40,000 40,000 40,000  2014 Term Loan Mar. 24, 2021 — — — 1,447,500 1,451,119 1,439,373  2015 Term Loan Jun. 10, 2022 — — — 487,500 488,109 480,801  2018 Term Loan Apr. 11, 2025 2,394,000 2,394,000 2,372,581 — — —  Total debt $ 9,829,000 $ 9,695,716 $ 9,734,145 $ 9,405,000 $ 9,436,290 $ 9,310,686  Less: current maturities of long-term debt (24,000) (20,000)  Total long-term debt, net of current maturities $ 9,710,145 $ 9,290,686 
Schedule of Cash and Non-Cash Interest Expense	   For the three months ended September 30, For the nine months ended September 30,  2018 2017 2018 2017  Cash Non-cash Cash Non-cash Cash Non-cash Cash Non-cash  Interest Interest Interest Interest Interest Interest Interest Interest   (in thousands)  2014 Senior Notes $ 9,141 $ 191 $ 9,141 $ 182 $ 27,422 $ 567 $ 27,422 $ 540  2016 Senior Notes 13,406 252 13,406 240 40,219 748 40,219 711  2017 Senior Notes 7,500 — — — 22,500 — — —  2012 Tower Securities — — — — — — 5,331 —  2013 Tower Securities 5,396 — 10,804 — 20,267 — 32,413 —  2014 Tower Securities 12,785 — 12,785 — 38,354 — 38,354 —  2015-1C Tower Securities 3,985 — 3,985 — 11,954 — 11,954 —  2016-1C Tower Securities 5,090 — 5,090 — 15,271 — 15,271 —  2017-1C Tower Securities 6,096 — 6,096 — 18,268 — 11,098 —  2018-1C Tower Securities 5,570 — — — 12,502 — — —  Revolving Credit Facility 1,721 — 2,673 — 4,911 — 6,848 —  2014 Term Loan — — 12,964 133 15,550 146 36,291 391  2015 Term Loan — — 4,366 170 5,237 187 12,221 504  2018 Term Loan 25,096 189 — — 46,303 354 — —  Other (69) — 47 — (480) — (7) —  Total $ 95,717 $ 632 $ 81,357 $ 725 $ 278,278 $ 2,002 $ 237,415 $ 2,146 

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Stock-Based Compensation [Abstract]
Schedule of Assumptions Used to Estimate Fair Value of Stock Options	   For the nine months ended  September 30,  2018 2017   Risk free interest rate 2.57% - 2.87% 1.70% - 1.97%  Dividend yield 0.7% 0.0%  Expected volatility 22% 20%  Expected lives 4.6 years 4.6 years 
Summary of Stock Option Activity	   Weighted- Weighted-Average  Average Remaining  Number Exercise Price Contractual Aggregate  of Shares Per Share Life (in years) Intrinsic Value  Outstanding at December 31, 2017 4,842 $ 100.12  Granted 937 $ 156.54  Exercised (548) $ 81.99  Forfeited/canceled (38) $ 123.91  Outstanding at September 30, 2018 5,193 $ 112.05 4.3 $ 252,235  Exercisable at September 30, 2018 2,538 $ 97.34 3.1 $ 160,627  Unvested at September 30, 2018 2,655 $ 126.11 5.4 $ 91,608 
Summary of Restricted Stock Unit Activity	   Weighted-Average  Number of Grant Date Fair  Shares Value per Share  (in thousands)  Outstanding at December 31, 2017 328 $ 110.20  Granted 137 $ 156.61  Vested (129) $ 110.94  Forfeited/canceled (11) $ 134.37  Outstanding at September 30, 2018 325 $ 128.73 

Segment Data (Tables)

Segment Data (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Data [Abstract]
Schedule of Segment Reporting Information	     Domestic Site Int'l Site Site Not Identified  Leasing Leasing Development by Segment Total   For the three months ended September 30, 2018 (in thousands)  Revenues $ 353,502 $ 81,758 $ 31,961 $ — $ 467,221  Cost of revenues (2) 66,862 25,432 24,447 — 116,741  Operating profit 286,640 56,326 7,514 — 350,480  Selling, general, and administrative 17,763 6,734 3,934 6,477 34,908  Acquisition related adjustments and expenses 1,887 1,108 — — 2,995  Asset impairment and decommission costs 2,801 4,067 — — 6,868  Depreciation, amortization and accretion 129,246 36,310 646 1,501 167,703  Operating income (loss) 134,943 8,107 2,934 (7,978) 138,006  Other expense (principally interest expense  and other income (expense)) (123,841) (123,841)  Income before income taxes 14,165  Cash capital expenditures (3) 33,794 120,176 425 666 155,061   For the three months ended September 30, 2017  Revenues $ 328,395 $ 80,143 $ 25,407 $ — $ 433,945  Cost of revenues (2) 65,226 25,125 21,117 — 111,468  Operating profit 263,169 55,018 4,290 — 322,477  Selling, general, and administrative 16,945 6,658 3,826 5,130 32,559  Acquisition related adjustments and expenses 962 621 — — 1,583  Asset impairment and decommission costs 7,898 1,554 (35) — 9,417  Depreciation, amortization and accretion 125,142 34,548 605 1,612 161,907  Operating income (loss) 112,222 11,637 (106) (6,742) 117,011  Other expense (principally interest expense  and other income (expense)) (64,472) (64,472)  Income before income taxes 52,539  Cash capital expenditures (3) 57,352 57,507 372 724 115,955      Not  Domestic Site Int'l Site Site Identified by  Leasing Leasing Development Segment Total   For the nine months ended September 30, 2018 (in thousands)  Revenues $ 1,041,892 $ 253,794 $ 86,160 $ — $ 1,381,846  Cost of revenues (2) 199,633 79,167 67,693 — 346,493  Operating profit 842,259 174,627 18,467 — 1,035,353  Selling, general, and administrative 55,047 20,242 11,943 19,669 106,901  Acquisition related adjustments and expenses 5,242 3,929 — — 9,171  Asset impairment and decommission costs 15,971 6,475 332 — 22,778  Depreciation, amortization and accretion 382,490 113,550 1,936 4,683 502,659  Operating income (loss) 383,509 30,431 4,256 (24,352) 393,844  Other expense (principally interest expense  and other income (expense)) (415,191) (415,191)  Loss before income taxes (21,347)  Cash capital expenditures (3) 287,711 218,739 1,345 2,148 509,943   For the nine months ended September 30, 2017  Revenues $ 974,850 $ 234,239 $ 75,513 $ — $ 1,284,602  Cost of revenues (2) 195,903 73,167 62,713 — 331,783  Operating profit 778,947 161,072 12,800 — 952,819  Selling, general, and administrative 53,147 19,007 11,495 16,528 100,177  Acquisition related adjustments and expenses 4,300 2,557 — — 6,857  Asset impairment and decommission costs 22,746 2,956 206 — 25,908  Depreciation, amortization and accretion 373,262 100,388 1,968 4,839 480,457  Operating income (loss) 325,492 36,164 (869) (21,367) 339,420  Other expense (principally interest expense  and other income (expense)) (233,259) (233,259)  Income before income taxes 106,161  Cash capital expenditures (3) 160,814 103,609 692 2,456 267,571       Domestic Site Int'l Site Site Not Identified  Leasing Leasing Development by Segment (1) Total   Assets (in thousands)  As of September 30, 2018 $ 5,093,302 $ 1,988,380 $ 51,494 $ 80,647 $ 7,213,823  As of December 31, 2017 $ 5,171,190 $ 2,028,479 $ 49,487 $ 71,049 $ 7,320,205  (1) Assets not identified by segment consist primarily of general corporate assets. (2) Excludes depreciation, amortization, and accretion. (3) Includes cash paid for capital expenditures and acquisitions and vehicle capital lease additions.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Weighted-Average Shares of Common Stock Outstanding used in Calculation of Basic and Diluted Earnings Per Share	   For the three months For the nine months  ended September 30, ended September 30,  2018 2017 2018 2017  Numerator:  Net income (loss) $ 16,144 $ 49,161 $ (9,702) $ 95,994  Denominator:  Basic weighted-average shares outstanding 114,597 119,746 115,378 120,745  Dilutive impact of stock options and restricted shares 1,517 1,280 — 982  Diluted weighted-average shares outstanding 116,114 121,026 115,378 121,727  Net income (loss) per common share:  Basic $ 0.14 $ 0.41 $ (0.08) $ 0.80  Diluted $ 0.14 $ 0.41 $ (0.08) $ 0.79 

Basis of Presentation (Narrativ

Basis of Presentation (Narrative) (Details) $ in Thousands	1 Months Ended		3 Months Ended			9 Months Ended
	Dec. 31, 2017USD ($)item	Nov. 30, 2014USD ($)item	Sep. 30, 2018USD ($)	Jun. 30, 2018	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)entity	Sep. 30, 2017USD ($)
Basis Of Presentation [Line Items]
Accounts receivable, net	$ 90,673		$ 89,302			$ 89,302
Remeasurement of amounts into functional currency				0.0347
Number of wholly owned subsidiaries that entered into intercompany loan agreement | entity						2
Intercompany loan maximum lend/borrow amount	$ 500,000	$ 750,000
Number of towers acquired | item	941	1,641
Gain (loss) on remeasurement of U.S. dollar denominated intercompany loan			(25,900)		$ 18,400	$ (113,138)	$ 11,649
Intercompany foreign currency outstanding balance			536,900			$ 536,900
Site Leasing [Member] | Revenue [Member]
Basis Of Presentation [Line Items]
Concentration risk percentage						94.00%
Site Development [Member]
Basis Of Presentation [Line Items]
Accounts receivable, net	$ 20,800		$ 23,200			$ 23,200
Site Development [Member] | Revenue [Member]
Basis Of Presentation [Line Items]
Concentration risk percentage						6.00%
Minimum [Member]
Basis Of Presentation [Line Items]
Lease term						5 years
Maximum [Member]
Basis Of Presentation [Line Items]
Lease term						10 years
Maximum [Member] | Revenue [Member] | Geographic Concentration Risk [Member] | Argentina [Member]
Basis Of Presentation [Line Items]
Concentration risk percentage				1.00%
Maximum [Member] | Assets [Member] | Geographic Concentration Risk [Member] | Argentina [Member]
Basis Of Presentation [Line Items]
Concentration risk percentage				1.00%

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accrued earnouts	$ 1.9	$ 1.9	$ 2.5
Performance targets, maximum potential obligation	14.2	14.2	11.1
Treasury securities			0.2
Held-to-maturity investments, carrying value	0.2	0.2	0.5
Held-to-maturity investments, fair value	0.2	0.2	0.5
Purchase and sale of short-term investments	95	95
Business Combinations and Asset Acquisitions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Performance targets, maximum potential obligation	$ 2.4	$ 2.4	$ 3.1
Revolving Credit Facility [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Basis spread on variable interest rate		1.125%
Revolving Credit Facility [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Basis spread on variable interest rate		1.75%

Fair Value Measurements (Summar

Fair Value Measurements (Summary of Asset Impairment and Decommission Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Asset impairment	$ 2,909	$ 4,128	$ 13,291	$ 10,162
Other (including third party decommission costs)	398	793	1,555	3,603
Total asset impairment and decommission costs	6,868	9,417	22,778	25,908
Decommissioned Towers [Member]
Write-offs relating to long-lived assets and intangibles	$ 3,561	$ 4,496	$ 7,932	$ 12,143

Restricted Cash (Narrative) (De

Restricted Cash (Narrative) (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Restricted Cash And Cash Equivalents Items [Line Items]
Surety, payment and performance bonds	$ 40,400,000	$ 39,500,000
Collateral payment for performance bonds	0	0
Collateral related to workers compensation policy	$ 2,300,000	$ 2,500,000

Restricted Cash (Schedule of Ca

Restricted Cash (Schedule of Cash, Cash Equivalents and Restricted Cash) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Restricted Cash And Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 136,221	$ 68,783
Restricted cash - current asset	24,700	32,924
Total cash, cash equivalents, and restricted cash	163,324	104,295	$ 172,462	$ 185,970
Securitization Escrow Accounts [Member] | Restricted Cash - Current Asset [Member]
Restricted Cash And Cash Equivalents Items [Line Items]
Restricted cash - current asset	24,504	32,699
Payment and Performance Bonds [Member] | Restricted Cash - Current Asset [Member]
Restricted Cash And Cash Equivalents Items [Line Items]
Restricted cash - current asset	196	225
Surety Bonds and Workers Compensation [Member] | Other Assets - Noncurrent [Member]
Restricted Cash And Cash Equivalents Items [Line Items]
Restricted cash - noncurrent asset	$ 2,403	$ 2,588

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets and Other Assets (Schedule of Prepaid Expense and Other Current Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Prepaid Expenses and Other Current Assets and Other Assets [Abstract]
Prepaid ground rent	$ 31,323	$ 32,505
Loan receivables	10,877	948
Other	17,441	16,263
Total prepaid expenses and other current assets	$ 59,641	$ 49,716

Prepaid Expenses and Other Cu_4

Prepaid Expenses and Other Current Assets and Other Assets (Schedule Of Other Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Prepaid Expenses and Other Current Assets and Other Assets [Abstract]
Prepaid ground rent	$ 252,506	$ 220,493
Straight-line rent receivable	317,422	313,650
Loan receivables	45,300	52,383
Deferred lease costs, net	26,682	27,703
Deferred tax asset - long term	28,130	1,670
Other	40,451	34,296
Total other assets	$ 710,491	$ 650,195

Acquisitions (Narrative) (Detai

Acquisitions (Narrative) (Details) $ in Millions	1 Months Ended			9 Months Ended
	Oct. 31, 2018USD ($)item	Dec. 31, 2017item	Nov. 30, 2014item	Sep. 30, 2018USD ($)item
Business Acquisition [Line Items]
Number of towers acquired | item		941	1,641
Other Acquisitions [Member]
Business Acquisition [Line Items]
Number of towers acquired | item				1,237
Property and equipment				$ 124.3
Intangible assets				262.6
Working capital adjustments				$ 14.9
Subsequent Event [Member]
Business Acquisition [Line Items]
Number of towers acquired | item	46
Cash paid for acquisition	$ 17.1

Acquisitions (Schedule of Acqui

Acquisitions (Schedule of Acquisition Capital Expenditures) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Acquisitions [Abstract]
Acquisitions of towers and related intangible assets	$ 110,464	$ 66,338	$ 372,054	$ 124,476
Land buyouts and other assets	8,008	12,488	31,781	36,531
Total cash acquisition capital expenditures	118,472	78,826	403,835	161,007
Acquisition costs paid through the issuance of common stock				$ 63,300
Common stock issued for acquisition costs				487,963
Unfunded towers and related intangible assets acquisitions				$ 21,000
Ground lease extensions	$ 6,700	$ 2,400	$ 16,400	$ 10,600

Intangible Assets, Net (Narrati

Intangible Assets, Net (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Intangible Assets, Net [Abstract]
Intangible assets, useful life			15 years
Amortization expense	$ 100.1	$ 96.8	$ 301.7	$ 286.8

Intangible Assets, Net (Gross a

Intangible Assets, Net (Gross and Net Carrying Amounts for each Major Class of Intangible Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 6,010,327	$ 5,972,612
Accumulated amortization	(2,622,372)	(2,374,481)
Net book value	3,387,955	3,598,131
Current Contract Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	4,349,404	4,355,171
Accumulated amortization	(1,846,918)	(1,673,270)
Net book value	2,502,486	2,681,901
Network Location Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,660,923	1,617,441
Accumulated amortization	(775,454)	(701,211)
Net book value	$ 885,469	$ 916,230

Property and Equipment, Net (Na

Property and Equipment, Net (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Property and Equipment, Net [Abstract]
Depreciation expense	$ 67.5	$ 65	$ 200.6	$ 193.2
Non-cash capital expenditures			$ 10.5		$ 12.4

Property and Equipment, Net (Pr

Property and Equipment, Net (Property and Equipment, Net (Including Assets Held Under Capital Leases)) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 5,644,307	$ 5,491,126
Less: accumulated depreciation	(2,856,593)	(2,678,780)
Property and equipment, net	2,787,714	2,812,346
Towers and Related Components [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	4,897,273	4,772,807
Construction-In-Process [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	35,336	34,689
Furniture, equipment and vehicles [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	54,880	53,260
Land, Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 656,818	$ 630,370

Costs and Estimated Earnings _3

Costs and Estimated Earnings on Uncompleted Contracts (Narrative) (Details) - customer	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Costs and Estimated Earnings on Uncompleted Contracts [Abstract]
Costs and estimated earnings in excess of billings on uncompleted contracts, net of billings in excess of costs and estimated earnings, percentage comprised by significant customers	95.10%	87.90%
Number of significant customers	8	8

Costs and Estimated Earnings _4

Costs and Estimated Earnings on Uncompleted Contracts (Summary of Costs and Estimated Earnings on Uncompleted Contracts) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Costs and Estimated Earnings on Uncompleted Contracts [Abstract]
Costs incurred on uncompleted contracts	$ 33,784	$ 31,404
Estimated earnings	13,662	10,541
Billings to date	(30,193)	(24,771)
Costs and estimated earnings on uncompleted contracts	$ 17,253	$ 17,174

Costs and Estimated Earnings _5

Costs and Estimated Earnings on Uncompleted Contracts (Costs and Estimated Earnings on Uncompleted Contracts Accompanying Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Costs and Estimated Earnings on Uncompleted Contracts [Abstract]
Costs and estimated earnings in excess of billings on uncompleted contracts	$ 17,799	$ 17,437
Billings in excess of costs and estimated earnings on uncompleted contracts (included in Other current liabilities)	(546)	(263)
Costs and estimated earnings on uncompleted contracts	$ 17,253	$ 17,174

Accrued Expenses (Schedule of A

Accrued Expenses (Schedule of Accrued Expenses) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accrued Expenses [Abstract]
Accrued earnouts on business combinations	$ 1,875	$ 2,470
Salaries and benefits	11,453	13,506
Real estate and property taxes	9,529	7,125
Non-cash capital expenditures	10,465	12,408
Other	34,807	34,353
Total accrued expenses	$ 68,129	$ 69,862

Debt (Senior Credit Agreement)

Debt (Senior Credit Agreement) (Narrative) (Details) - USD ($)	Apr. 11, 2018	Oct. 13, 2017	Oct. 31, 2018	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Nov. 08, 2018	Mar. 31, 2018
Line of Credit Facility [Line Items]
Repayments of revolving credit facility					$ 725,000,000	$ 375,000,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,250,000,000							$ 1,000,000,000
Revolving credit facility, maturity date					Apr. 11, 2023
Line of credit facility, commitment fee					0.25%
Borrowings on the revolving credit facility				$ 260,000,000	$ 805,000,000
Repayments of revolving credit facility		$ 460,000,000		225,000,000	725,000,000
Line of credit facility, outstanding				$ 120,000,000	$ 120,000,000
Revolving credit facility, effective interest rate				3.88%	3.88%
Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Borrowings on the revolving credit facility			$ 95,000,000
Line of credit facility, outstanding							$ 215,000,000
Minimum [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate					1.125%
Line of credit facility, commitment fee					0.20%
Minimum [Member] | Revolving Credit Facility [Member] | Base Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate					0.125%
Maximum [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate					1.75%
Line of credit facility, commitment fee					0.25%
Maximum [Member] | Revolving Credit Facility [Member] | Base Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate					0.75%
2018 Term Loan [Member]
Line of Credit Facility [Line Items]
Debt instrument, face amount	$ 2,400,000,000
2018 Term Loan [Member] | Eurodollar [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	2.00%
2018 Term Loan [Member] | Base Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	1.00%

Debt (Term Loans under the Seni

Debt (Term Loans under the Senior Credit Agreement) (Narrative) (Details) - USD ($)	Apr. 11, 2018	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Debt instrument, principal balance		$ 9,829,000,000		$ 9,829,000,000		$ 9,405,000,000
Repayment of term loans				1,941,000,000	$ 15,000,000
2014 Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 1,500,000,000		$ 1,500,000,000
Debt instrument, maturity date				Mar. 24, 2021
Term Loan, percentage of par value		99.75%		99.75%
Quarterly payments				$ 3,800,000
Debt instrument, principal balance						1,447,500,000
Repayment of term loans	$ 1,443,800,000		$ 3,800,000
Financing fees		14,100,000		14,100,000
Write-off of deferred financing fees	5,800,000
Discount related to debt	1,700,000
2015 Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 500,000,000		$ 500,000,000
Debt instrument, maturity date				Jun. 10, 2022
Term Loan, percentage of par value		99.00%		99.00%
Quarterly payments				$ 1,300,000
Debt instrument, principal balance						$ 487,500,000
Repayment of term loans	486,300,000		$ 1,300,000
Financing fees		$ 5,500,000		$ 5,500,000
Write-off of deferred financing fees	3,200,000
Discount related to debt	3,100,000
2018 Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 2,400,000,000
Debt instrument, maturity date				Apr. 11, 2025
Term Loan, percentage of par value	99.75%
Accruing interest rate during the period				4.25%
Quarterly payments				$ 6,000,000
Debt instrument, principal balance		2,394,000,000		2,394,000,000
Repayment of term loans		6,000,000		6,000,000
Financing fees		$ 16,700,000		$ 16,700,000
2014 and 2015 Term Loans [Member]
Debt Instrument [Line Items]
Repayment of term loans	$ 1,930,000,000
Base Rate [Member] | 2014 Term Loan [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				1.25%
Rate floor		0.00%		0.00%
Base Rate [Member] | 2015 Term Loan [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				1.25%
Rate floor		0.00%		0.00%
Base Rate [Member] | 2018 Term Loan [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate	1.00%
Rate floor	0.00%
Eurodollar [Member] | 2014 Term Loan [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				2.25%
Rate floor		0.00%		0.00%
Eurodollar [Member] | 2015 Term Loan [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				2.25%
Rate floor		0.00%		0.00%
Eurodollar [Member] | 2018 Term Loan [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate	2.00%
Rate floor	0.00%

Debt (Secured Tower Revenue Sec

Debt (Secured Tower Revenue Securities) (Narrative) (Details) - USD ($)	Mar. 09, 2018	Apr. 17, 2017	Jul. 07, 2016	Oct. 14, 2015	Oct. 15, 2014	Apr. 18, 2013	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt							$ 9,734,145,000	$ 9,310,686,000
2012-1C Tower Securities [Member]
Debt Instrument [Line Items]
Repayments of long-term debt		$ 610,000,000
2013 Tower Securities [Member]
Debt Instrument [Line Items]
Financing fees						$ 25,500,000
Debt instrument, weighted average interest rate						3.218%
Long-term debt						$ 1,330,000,000
2013-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 425,000,000
Debt instrument, interest rate, stated percentage						2.24%
Repayment date of debt instrument						Apr. 10, 2018
Debt instrument, maturity date						Apr. 9, 2043	Apr. 10, 2018
Repayments of long-term debt	$ 425,000,000
Long-term debt								424,482,000
2013-2C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 575,000,000
Debt instrument, interest rate, stated percentage						3.722%
Repayment date of debt instrument						Apr. 11, 2023
Debt instrument, maturity date						Apr. 9, 2048	Apr. 11, 2023
Long-term debt							$ 569,434,000	568,609,000
2013-1D Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount						$ 330,000,000
Debt instrument, interest rate, stated percentage						3.598%
Repayment date of debt instrument						Apr. 10, 2018
Debt instrument, maturity date						Apr. 9, 2043	Apr. 10, 2018
Repayments of long-term debt	330,000,000
Long-term debt								329,585,000
2014 Tower Securities [Member]
Debt Instrument [Line Items]
Financing fees					$ 22,500,000
Debt instrument, weighted average interest rate					3.289%
Long-term debt					$ 1,540,000,000
2014-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount					$ 920,000,000
Debt instrument, interest rate, stated percentage					2.898%
Repayment date of debt instrument					Oct. 8, 2019
Debt instrument, maturity date					Oct. 11, 2044		Oct. 8, 2019
Long-term debt							$ 917,020,000	914,929,000
2014-2C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount					$ 620,000,000
Debt instrument, interest rate, stated percentage					3.869%
Repayment date of debt instrument					Oct. 8, 2024
Debt instrument, maturity date					Oct. 8, 2049		Oct. 8, 2024
Long-term debt							$ 614,099,000	613,461,000
2015-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount				$ 500,000,000
Debt instrument, interest rate, stated percentage				3.156%
Repayment date of debt instrument				Oct. 8, 2020
Debt instrument, maturity date				Oct. 10, 2045			Oct. 8, 2020
Financing fees				$ 11,200,000
Long-term debt							$ 495,162,000	493,474,000
2016-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 700,000,000
Debt instrument, interest rate, stated percentage			2.877%
Repayment date of debt instrument			Jul. 9, 2021
Debt instrument, maturity date			Jul. 10, 2046				Jul. 9, 2021
Financing fees			$ 9,500,000
Long-term debt							$ 694,519,000	693,118,000
2017-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 760,000,000
Debt instrument, interest rate, stated percentage		3.168%
Repayment date of debt instrument		Apr. 11, 2022
Debt instrument, maturity date		Apr. 9, 2047					Apr. 11, 2022
Financing fees		$ 10,200,000
Long-term debt							$ 752,530,000	$ 751,076,000
2017-1R Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 40,000,000
Debt instrument, interest rate, stated percentage		4.459%
Repayment date of debt instrument		Apr. 11, 2022
Debt instrument, maturity date		Apr. 9, 2047
2018-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 640,000,000
Debt instrument, interest rate, stated percentage	3.448%
Repayment date of debt instrument	Mar. 9, 2023
Debt instrument, maturity date	Mar. 9, 2048						Mar. 9, 2023
Financing fees	$ 8,500,000
Long-term debt							$ 632,339,000
2018-1R Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 33,700,000
Debt instrument, interest rate, stated percentage	4.949%
Repayment date of debt instrument	Mar. 9, 2023
Debt instrument, maturity date	Mar. 9, 2048
Mortgage Loan [Member]
Debt Instrument [Line Items]
Debt instrument, increase	$ 673,700,000
Debt instrument, decrease after giving effect to prepayment of loan components	$ 81,300,000

Debt (Senior Notes) (Narrative)

Debt (Senior Notes) (Narrative) (Details) - USD ($) $ in Thousands	Oct. 13, 2017	Aug. 15, 2016	Jul. 01, 2014	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Debt Instrument [Line Items]
Repayments of revolving credit facility					$ 725,000	$ 375,000
5.75% Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage		5.75%
Repayments of unsecured debt		$ 800,000
5.625% Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage		5.625%
Repayments of unsecured debt		$ 250,000
2014 Senior Notes [Member]
Debt Instrument [Line Items]
Unsecured senior notes			$ 750,000
Debt instrument, maturity date					Jul. 15, 2022
Debt instrument, interest rate, stated percentage			4.875%
Percentage of face value price for issuance of senior notes			99.178%
Interest payable dates					January 15 and July 15
Financing fees			$ 11,600
2014 Senior Notes [Member] | Redemption, Period Two [Member]
Debt Instrument [Line Items]
Redemption price, percentage					102.438%
2014 Senior Notes [Member] | Redemption, Period Three [Member]
Debt Instrument [Line Items]
Redemption price, percentage					101.219%
2014 Senior Notes [Member] | Redemption, Period Four [Member]
Debt Instrument [Line Items]
Redemption price, percentage					100.00%
2016 Senior Notes [Member]
Debt Instrument [Line Items]
Unsecured senior notes		$ 1,100,000
Debt instrument, maturity date					Sep. 1, 2024
Debt instrument, interest rate, stated percentage		4.875%
Percentage of face value price for issuance of senior notes		99.178%
Interest payable dates					March 1 and September 1
Financing fees		$ 12,800
Redemption price, percentage					104.875%
2016 Senior Notes [Member] | Redemption, Period One [Member]
Debt Instrument [Line Items]
Redemption price, percentage					103.656%
2016 Senior Notes [Member] | Redemption, Period Two [Member]
Debt Instrument [Line Items]
Redemption price, percentage					102.438%
2016 Senior Notes [Member] | Redemption, Period Three [Member]
Debt Instrument [Line Items]
Redemption price, percentage					101.219%
2016 Senior Notes [Member] | Redemption, Period Four [Member]
Debt Instrument [Line Items]
Redemption price, percentage					100.00%
2017 Senior Notes [Member]
Debt Instrument [Line Items]
Unsecured senior notes	$ 750,000
Debt instrument, maturity date					Oct. 1, 2022
Debt instrument, interest rate, stated percentage	4.00%
Interest payable dates					April 1 and October 1
Financing fees	$ 8,900
Redemption price, percentage					104.00%
2017 Senior Notes [Member] | Redemption, Period One [Member]
Debt Instrument [Line Items]
Redemption price, percentage					102.00%
2017 Senior Notes [Member] | Redemption, Period Two [Member]
Debt Instrument [Line Items]
Redemption price, percentage					101.00%
2017 Senior Notes [Member] | Redemption, Period Three [Member]
Debt Instrument [Line Items]
Redemption price, percentage					100.00%
Maximum [Member] | 2016 Senior Notes [Member]
Debt Instrument [Line Items]
Aggregate redemption price, percentage					35.00%
Maximum [Member] | 2017 Senior Notes [Member]
Debt Instrument [Line Items]
Aggregate redemption price, percentage					35.00%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date					Apr. 11, 2023
Repayments of revolving credit facility	$ 460,000			$ 225,000	$ 725,000

Debt (Schedule of Principal Val

Debt (Schedule of Principal Values, Fair Values, and Carrying Values of Debt) (Details) - USD ($)	Mar. 09, 2018	Apr. 17, 2017	Jul. 07, 2016	Oct. 14, 2015	Oct. 15, 2014	Apr. 18, 2013	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Principal Balance							$ 9,829,000,000	$ 9,405,000,000
Fair Value							9,695,716,000	9,436,290,000
Carrying Value							9,734,145,000	9,310,686,000
Less: current maturities of long-term debt							(24,000,000)	(20,000,000)
Total long-term debt, net of current maturities							$ 9,710,145,000	9,290,686,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date							Apr. 11, 2023
Principal Balance							$ 120,000,000	40,000,000
Fair Value							120,000,000	40,000,000
Carrying Value							$ 120,000,000	40,000,000
2014 Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date							Jul. 15, 2022
Principal Balance							$ 750,000,000	750,000,000
Fair Value							756,563,000	770,625,000
Carrying Value							$ 740,714,000	739,079,000
2016 Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date							Sep. 1, 2024
Principal Balance							$ 1,100,000,000	1,100,000,000
Fair Value							1,083,500,000	1,127,500,000
Carrying Value							$ 1,083,071,000	1,081,262,000
2017 Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date							Oct. 1, 2022
Principal Balance							$ 750,000,000	750,000,000
Fair Value							734,063,000	750,938,000
Carrying Value							$ 742,676,000	741,437,000
2013-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date						Apr. 9, 2043	Apr. 10, 2018
Principal Balance								425,000,000
Fair Value								423,853,000
Carrying Value								424,482,000
2013-2C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date						Apr. 9, 2048	Apr. 11, 2023
Principal Balance							$ 575,000,000	575,000,000
Fair Value							560,108,000	578,433,000
Carrying Value							$ 569,434,000	568,609,000
2013-1D Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date						Apr. 9, 2043	Apr. 10, 2018
Principal Balance								330,000,000
Fair Value								330,145,000
Carrying Value								329,585,000
2014-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date					Oct. 11, 2044		Oct. 8, 2019
Principal Balance							$ 920,000,000	920,000,000
Fair Value							909,080,000	915,216,000
Carrying Value							$ 917,020,000	914,929,000
2014-2C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date					Oct. 8, 2049		Oct. 8, 2024
Principal Balance							$ 620,000,000	620,000,000
Fair Value							599,298,000	620,942,000
Carrying Value							$ 614,099,000	613,461,000
2015-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date				Oct. 10, 2045			Oct. 8, 2020
Principal Balance							$ 500,000,000	500,000,000
Fair Value							489,080,000	496,840,000
Carrying Value							$ 495,162,000	493,474,000
2016-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date			Jul. 10, 2046				Jul. 9, 2021
Principal Balance							$ 700,000,000	700,000,000
Fair Value							683,991,000	691,166,000
Carrying Value							$ 694,519,000	693,118,000
2017-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date		Apr. 9, 2047					Apr. 11, 2022
Principal Balance							$ 760,000,000	760,000,000
Fair Value							734,244,000	751,404,000
Carrying Value							$ 752,530,000	751,076,000
2018-1C Tower Securities [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date	Mar. 9, 2048						Mar. 9, 2023
Principal Balance							$ 640,000,000
Fair Value							631,789,000
Carrying Value							$ 632,339,000
2014 Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date							Mar. 24, 2021
Principal Balance								1,447,500,000
Fair Value								1,451,119,000
Carrying Value								1,439,373,000
2015 Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date							Jun. 10, 2022
Principal Balance								487,500,000
Fair Value								488,109,000
Carrying Value								$ 480,801,000
2018 Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date							Apr. 11, 2025
Principal Balance							$ 2,394,000,000
Fair Value							2,394,000,000
Carrying Value							$ 2,372,581,000

Debt (Schedule of Cash and Non-

Debt (Schedule of Cash and Non-Cash Interest Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Debt Instrument [Line Items]
Cash Interest	$ 95,717	$ 81,357	$ 278,278	$ 237,415
Non-cash Interest	632	725	2,002	2,146
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Cash Interest	1,721	2,673	4,911	6,848
2014 Senior Notes [Member]
Debt Instrument [Line Items]
Cash Interest	9,141	9,141	27,422	27,422
Non-cash Interest	191	182	567	540
2016 Senior Notes [Member]
Debt Instrument [Line Items]
Cash Interest	13,406	13,406	40,219	40,219
Non-cash Interest	252	240	748	711
2017 Senior Notes [Member]
Debt Instrument [Line Items]
Cash Interest	7,500		22,500
2012 Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest				5,331
2013 Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest	5,396	10,804	20,267	32,413
2014 Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest	12,785	12,785	38,354	38,354
2015-1C Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest	3,985	3,985	11,954	11,954
2016-1C Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest	5,090	5,090	15,271	15,271
2017-1C Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest	6,096	6,096	18,268	11,098
2018-1C Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest	5,570		12,502
2014 Term Loan [Member]
Debt Instrument [Line Items]
Cash Interest		12,964	15,550	36,291
Non-cash Interest		133	146	391
2015 Term Loan [Member]
Debt Instrument [Line Items]
Cash Interest		4,366	5,237	12,221
Non-cash Interest		170	187	504
2018 Term Loan [Member]
Debt Instrument [Line Items]
Cash Interest	25,096		46,303
Non-cash Interest	189		354
Other [Member]
Debt Instrument [Line Items]
Cash Interest	$ (69)	$ 47	$ (480)	$ (7)

Shareholders' Equity (Narrative

Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Oct. 31, 2018	Sep. 30, 2018	Sep. 30, 2018	Nov. 08, 2018	Feb. 16, 2018
Class of Stock [Line Items]
Stock repurchase program, authorized					$ 1,000
Class A Common Stock [Member]
Class of Stock [Line Items]
Stock repurchased, shares		0.7	2.8
Stock repurchased, value		$ 108	$ 453.5
Weighted average price per share		$ 155.16	$ 161.23
Class A Common Stock [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Stock repurchased, shares	0.9
Stock repurchased, value	$ 142
Weighted average price per share	$ 151.55
Stock repurchase program, remaining authorization				$ 404.5
Previous Stock Repurchase Program [Member]
Class of Stock [Line Items]
Stock repurchase program, remaining authorization					$ 150

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)$ / shares
Stock-Based Compensation [Abstract]
Weighted-average fair value of options granted | $ / shares	$ 33
Total intrinsic value for options exercised | $	$ 44.2

Stock-Based Compensation (Sched

Stock-Based Compensation (Schedule of Assumptions used to Estimate Fair Value of Stock Options) (Details)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Stock-Based Compensation [Abstract]
Risk free interest rate, Minimum	2.57%	1.70%
Risk free interest rate, Maximum	2.87%	1.97%
Dividend yield	0.70%	0.00%
Expected volatility	22.00%	20.00%
Expected lives	4 years 7 months 6 days	4 years 7 months 6 days

Stock-Based Compensation (Summa

Stock-Based Compensation (Summary of Stock Option Activity) (Details) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)$ / sharesshares
Stock-Based Compensation [Abstract]
Number of Shares, Outstanding at December 31, 2017 | shares	4,842
Number of Shares, Granted | shares	937
Number of Shares, Exercised | shares	(548)
Number of Shares, Forfeited/canceled | shares	(38)
Number of Shares,Outstanding at September 30, 2018 | shares	5,193
Number of Shares, Exercisable at September 30, 2018 | shares	2,538
Number of Shares, Unvested at September 30, 2018 | shares	2,655
Weighted-Average Exercise Price Per Share, Outstanding at December 31, 2017 | $ / shares	$ 100.12
Weighted-Average Exercise Price Per Share, Granted | $ / shares	156.54
Weighted-Average Exercise Price Per Share, Exercised | $ / shares	81.99
Weighted-Average Exercise Price Per Share, Forfeited/canceled | $ / shares	123.91
Weighted-Average Exercise Price Per Share, Outstanding at September 30, 2018 | $ / shares	112.05
Weighted-Average Exercise Price Per Share, Exercisable at September 30, 2018 | $ / shares	97.34
Weighted-Average Exercise Price Per Share, Unvested at September 30, 2018 | $ / shares	$ 126.11
Weighted-Average Remaining Contractual Life (in years), Outstanding at September 30, 2018	4 years 3 months 18 days
Weighted-Average Remaining Contractual Life (in years), Exercisable at September 30, 2018	3 years 1 month 6 days
Weighted-Average Remaining Contractual Life (in years), Unvested at September 30, 2018	5 years 4 months 24 days
Aggregate Intrinsic Value, Outstanding at September 30, 2018 | $	$ 252,235
Aggregate Intrinsic Value, Exercisable at September 30, 2018 | $	160,627
Aggregate Intrinsic Value, Unvested at September 30, 2018 | $	$ 91,608

Stock-Based Compensation (Sum_2

Stock-Based Compensation (Summary of Restricted Stock Unit Activity) (Details) shares in Thousands	9 Months Ended
	Sep. 30, 2018$ / sharesshares
Stock-Based Compensation [Abstract]
Number of Shares, Outstanding at December 31, 2017 | shares	328
Number of Shares, Granted | shares	137
Number of Shares, Vested | shares	(129)
Number of Shares, Forfeited/canceled | shares	(11)
Number of Shares, Outstanding at September 30, 2018 | shares	325
Weighted-Average Grant Date Fair Value per Share, Outstanding at December 31, 2017 | $ / shares	$ 110.20
Weighted-Average Grant Date Fair Value per Share, Granted | $ / shares	156.61
Weighted-Average Grant Date Fair Value per Share, Vested | $ / shares	110.94
Weighted-Average Grant Date Fair Value per Share, Forfeited/canceled | $ / shares	134.37
Weighted-Average Grant Date Fair Value per Share, Outstanding at September 30, 2018 | $ / shares	$ 128.73

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Income Taxes [Abstract]
Net foreign operating loss carry-forward				$ 1,000
Effective income tax rate			21.00%	35.00%
GILTI provisional amounts	$ 12.9	$ 35.7

Segment Data (Narrative) (Detai

Segment Data (Narrative) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)segment	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Segment Reporting Information [Line Items]
Number of business segments | segment			2
Site leasing	$ 435,260	$ 408,538	$ 1,295,686	$ 1,209,089
Total assets	7,213,823		7,213,823		$ 7,320,205
International Site Leasing [Member]
Segment Reporting Information [Line Items]
Total assets	1,988,380		1,988,380		2,028,479
Brazil [Member]
Segment Reporting Information [Line Items]
Site leasing			167,100	$ 162,300
Total assets	$ 1,003,600		$ 1,003,600		$ 1,278,900

Segment Data (Schedule of Segme

Segment Data (Schedule of Segment Reporting Information) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues		$ 467,221	$ 433,945	$ 1,381,846	$ 1,284,602
Cost of revenues		116,741	111,468	346,493	331,783
Operating profit		350,480	322,477	1,035,353	952,819
Selling, general, and administrative	[1]	34,908	32,559	106,901	100,177
Acquisition related adjustments and expenses		2,995	1,583	9,171	6,857
Asset impairment and decommission costs		6,868	9,417	22,778	25,908
Depreciation, amortization and accretion		167,703	161,907	502,659	480,457
Operating income		138,006	117,011	393,844	339,420
Other expense (principally interest expense and other income (expense))		(123,841)	(64,472)	(415,191)	(233,259)
Income (loss) before income taxes		14,165	52,539	(21,347)	106,161
Cash capital expenditures		155,061	115,955	509,943	267,571
Assets		7,213,823		7,213,823		$ 7,320,205
Domestic Site Leasing [Member]
Segment Reporting Information [Line Items]
Revenues		353,502	328,395	1,041,892	974,850
Cost of revenues		66,862	65,226	199,633	195,903
Operating profit		286,640	263,169	842,259	778,947
Selling, general, and administrative		17,763	16,945	55,047	53,147
Acquisition related adjustments and expenses		1,887	962	5,242	4,300
Asset impairment and decommission costs		2,801	7,898	15,971	22,746
Depreciation, amortization and accretion		129,246	125,142	382,490	373,262
Operating income		134,943	112,222	383,509	325,492
Cash capital expenditures		33,794	57,352	287,711	160,814
Assets		5,093,302		5,093,302		5,171,190
International Site Leasing [Member]
Segment Reporting Information [Line Items]
Revenues		81,758	80,143	253,794	234,239
Cost of revenues		25,432	25,125	79,167	73,167
Operating profit		56,326	55,018	174,627	161,072
Selling, general, and administrative		6,734	6,658	20,242	19,007
Acquisition related adjustments and expenses		1,108	621	3,929	2,557
Asset impairment and decommission costs		4,067	1,554	6,475	2,956
Depreciation, amortization and accretion		36,310	34,548	113,550	100,388
Operating income		8,107	11,637	30,431	36,164
Cash capital expenditures		120,176	57,507	218,739	103,609
Assets		1,988,380		1,988,380		2,028,479
Site Development [Member]
Segment Reporting Information [Line Items]
Revenues		31,961	25,407	86,160	75,513
Cost of revenues		24,447	21,117	67,693	62,713
Operating profit		7,514	4,290	18,467	12,800
Selling, general, and administrative		3,934	3,826	11,943	11,495
Asset impairment and decommission costs			(35)	332	206
Depreciation, amortization and accretion		646	605	1,936	1,968
Operating income		2,934	(106)	4,256	(869)
Cash capital expenditures		425	372	1,345	692
Assets		51,494		51,494		49,487
Not Identified by Segment [Member]
Segment Reporting Information [Line Items]
Selling, general, and administrative		6,477	5,130	19,669	16,528
Depreciation, amortization and accretion		1,501	1,612	4,683	4,839
Operating income		(7,978)	(6,742)	(24,352)	(21,367)
Other expense (principally interest expense and other income (expense))		(123,841)	(64,472)	(415,191)	(233,259)
Cash capital expenditures		666	$ 724	2,148	$ 2,456
Assets		$ 80,647		$ 80,647		$ 71,049
[1]	Includes non-cash compensation of $10,261 and $9,213 for the three months ended September 30, 2018 and 2017, respectively, and $31,188 and $28,069 for the nine months ended September 30, 2018 and 2017, respectively.

Earnings Per Share (Narrative)

Earnings Per Share (Narrative) (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from earnings per share calculation	900,000	11,674	5,200,000	1,800,000
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from earnings per share calculation			300,000

Earnings Per Share (Weighted-Av

Earnings Per Share (Weighted-Average Shares of Common Stock Outstanding used in Calculation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income (loss)	$ 16,144	$ 49,161	$ (9,702)	$ 95,994
Basic weighted-average shares outstanding	114,597	119,746	115,378	120,745
Dilutive impact of stock options and restricted shares	1,517	1,280		982
Diluted weighted-average shares outstanding	116,114	121,026	115,378	121,727
Net income (loss) per common share
Basic	$ 0.14	$ 0.41	$ (0.08)	$ 0.80
Diluted	$ 0.14	$ 0.41	$ (0.08)	$ 0.79