LPL Financial (LPLA) 10-Q 30 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	9 Months Ended
	Sep. 30, 2018	Oct. 22, 2018
Entity Information [Line Items]
Entity Registrant Name	LPL Financial Holdings Inc.
Entity Central Index Key	1,397,911
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		86,711,957
Entity Emerging Growth Company	false
Entity Small Business	false

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Unaudited) - 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:
Commission	$ 486,875	$ 403,011	$ 1,449,771	$ 1,244,881
Advisory Revenue	458,087	356,945	1,319,391	1,033,319
Asset-based	248,895	183,953	706,834	514,626
Transaction and fee	118,941	103,999	352,045	321,522
Interest income, net of interest expense	10,512	6,162	28,426	17,931
Other	7,687	10,038	14,891	32,760
Total net revenues	1,330,997	1,064,108	3,871,358	3,165,039
EXPENSES:
Commission and advisory	821,950	663,765	2,384,266	1,971,874
Compensation and benefits	128,007	113,659	373,884	337,170
Promotional	52,628	42,935	163,462	111,595
Depreciation and amortization	22,838	21,996	65,759	63,933
Amortization of Intangible Assets	15,676	9,352	44,580	28,296
Occupancy and equipment	30,308	22,803	84,848	70,989
Professional services	23,129	16,438	61,223	50,732
Brokerage, clearing and exchange	15,844	13,491	47,154	41,567
Communications and data processing	12,334	10,866	34,546	32,525
Other	29,219	24,376	88,175	71,140
Total operating expenses	1,151,933	939,681	3,347,897	2,779,821
Non-operating interest expense	31,705	26,519	93,267	78,131
Loss on extinguishment of debt	0	1,268	0	22,407
INCOME BEFORE PROVISION FOR INCOME TAXES	147,359	96,640	430,194	284,680
PROVISION FOR INCOME TAXES	40,494	38,498	111,033	109,915
NET INCOME	$ 106,865	$ 58,142	$ 319,161	$ 174,765
EARNINGS PER SHARE (Note 12)
Earnings per share, basic	$ 1.22	$ 0.65	$ 3.59	$ 1.94
Earnings per share, diluted	$ 1.19	$ 0.63	$ 3.49	$ 1.90
Weighted-average shares outstanding, basic	87,426	89,967	88,841	90,029
Weighted-average shares outstanding, diluted	89,878	92,042	91,447	92,027

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
NET INCOME	$ 106,865	$ 58,142	$ 319,161	$ 174,765
Other comprehensive income, net of tax:
Unrealized gain on cash flow hedges, net of tax expense of $0, $0, $0 and $187 for the three and nine months ended September 30, 2018 and 2017, respectively	0	0	0	293
Reclassification adjustment for realized gain on cash flow hedges included in the condensed consolidated statements of income, net of tax expense of $0, $0, $0 and $406 for the three and nine months ended September 30, 2018 and 2017, respectively	0	0	0	(608)
Total other comprehensive income, net of tax	0	0	0	(315)
TOTAL COMPREHENSIVE INCOME	$ 106,865	$ 58,142	$ 319,161	$ 174,450

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Tax expense (benefit) on unrealized gain (loss) on cash flow hedges	$ 0	$ 0	$ 0	$ 187
Tax expense on adjustment for items reclassified to earnings	$ 0	$ 0	$ 0	$ (406)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Financial Condition (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
ASSETS
Cash and cash equivalents	$ 768,546	$ 811,136
Cash segregated under federal and other regulations	566,128	763,831
Restricted cash	58,754	50,688
Receivables from:
Clients, net of allowance of $621 at September 30, 2018 and $466 at December 31, 2017	435,133	344,230
Product sponsors, broker-dealers, and clearing organizations	213,887	196,207
Advisor loans, net of allowance of $3,539 at September 30, 2018 and $3,264 at December 31, 2017	261,214	219,157
Others, net of allowance of $8,997 at September 30, 2018 and $6,115 at December 31, 2017	236,480	228,986
Securities owned:
Trading — at fair value	32,455	17,879
Held-to-maturity — at amortized cost	13,005	11,833
Securities borrowed	6,274	12,489
Fixed assets, net of accumulated depreciation and amortization of $489,209 at September 30, 2018 and $427,344 at December 31, 2017	441,072	412,684
Goodwill	1,476,775	1,427,769
Intangible assets, net of accumulated amortization of $463,646 at September 30, 2018 and $419,066 at December 31, 2017	482,234	414,093
National Planning Holdings acquisition	0	162,500
Other assets	297,856	285,269
Total assets	5,289,813	5,358,751
LIABILITIES:
Drafts payable	195,343	185,929
Payables to clients	804,797	962,891
Payables to broker-dealers and clearing organizations	54,360	54,262
Accrued commission and advisory expenses payable	168,176	147,095
Accounts payable and accrued liabilities	486,573	461,149
Income taxes payable	22,531	469
Unearned revenue	82,546	72,222
Securities sold, but not yet purchased — at fair value	333	1,182
Long-term borrowing, net of unamortized debt issuance cost of $20,345 at September 30, 2018 and $22,812 at December 31, 2017	2,375,113	2,385,022
Leasehold Financing Obligation	105,057	107,518
Deferred income taxes, net	15,517	16,004
Total liabilities	4,310,346	4,393,743
STOCKHOLDERS' EQUITY:
Common stock, $.001 par value; 600,000,000 shares authorized; 124,611,205 shares issued at September 30, 2018 and 123,030,383 shares issued at December 31, 2017	124	123
Additional paid-in capital	1,621,020	1,556,117
Treasury stock, at cost — 37,901,990 shares at September 30, 2018 and 33,262,115 shares at December 31, 2017	(1,612,847)	(1,309,568)
Retained earnings	971,170	718,336
Total stockholders' equity	979,467	965,008
Total liabilities and stockholders' equity	$ 5,289,813	$ 5,358,751

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Financial Condition (Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accumulated depreciation and amortization, Fixed assets	$ 489,209	$ 427,344
Accumulated amortization, Intangible assets	463,646	419,066
Debt Issuance Costs, Net	$ 20,345	$ 22,812
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	600,000,000	600,000,000
Common stock, shares issued	124,611,205	123,030,383
Treasury stock, shares	37,901,990	33,262,115
Receivables from clients [Member]
Allowances on receivables	$ 621	$ 466
Receivables from others [Member]
Allowances on receivables	8,997	6,115
Advisor Loans [Member]
Allowances on receivables	$ 3,539	$ 3,264

Condensed Consolidated Statem_6

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
BEGINNING BALANCE at Dec. 31, 2016	$ 820,995	$ 120	$ 1,445,256	$ (1,194,645)	$ 315	$ 569,949
BEGINNING BALANCE, shares at Dec. 31, 2016		119,918,000		30,621,000
Net income and other comprehensive income (loss), net of tax expense	174,450				(315)	174,765
Issuance of common stock to settle restricted stock units, net	(3,155)	$ 0	0	$ (3,155)
Issuance of common stock to settle restricted stock units, net, shares		350,000		79,000
Treasury stock purchases	(83,721)			$ (83,721)
Treasury stock purchases, shares				2,017,000
Cash dividends on common stock	(67,765)					(67,765)
Stock option exercises and other (in shares)		2,558,000		(51,000)
Stock option exercises and other	77,876	$ 3	76,287	$ 1,821		(235)
Share-based compensation	21,885		21,885
ENDING BALANCE at Sep. 30, 2017	940,565	$ 123	1,543,428	$ (1,279,700)	0	676,714
ENDING BALANCE, shares at Sep. 30, 2017		122,826,000		32,666,000
BEGINNING BALANCE at Dec. 31, 2017	965,008	$ 123	1,556,117	$ (1,309,568)	0	718,336
BEGINNING BALANCE, shares at Dec. 31, 2017		123,030,000		33,262,000
Net income and other comprehensive income (loss), net of tax expense	319,161				0	319,161
Issuance of common stock to settle restricted stock units, net	(4,536)	$ 0	0	$ (4,536)
Issuance of common stock to settle restricted stock units, net, shares		356,000		70,000
Treasury stock purchases	$ (300,091)			$ (300,091)
Treasury stock purchases, shares	4,608,020			4,608,000
Cash dividends on common stock	$ (66,847)					(66,847)
Stock option exercises and other (in shares)	1,218,087,000	1,225,000		(38,000)
Stock option exercises and other	$ 43,248	$ 1	41,379	$ 1,348		520
Share-based compensation	23,524		23,524
ENDING BALANCE at Sep. 30, 2018	$ 979,467	$ 124	$ 1,621,020	$ (1,612,847)	$ 0	$ 971,170
ENDING BALANCE, shares at Sep. 30, 2018		124,611,000		37,902,000

Condensed Consolidated Statem_7

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 319,161	$ 174,765
Noncash items:
Depreciation and amortization	65,759	63,933
Amortization of Intangible Assets	44,580	28,296
Amortization of debt issuance costs	3,090	3,272
Share-based compensation	23,524	21,885
Provision for bad debts	5,335	2,993
Deferred income tax provision	(487)	(68)
Loss on extinguishment of debt	0	22,407
Loan forgiveness	50,695	39,713
Other	(334)	(11,875)
Changes in operating assets and liabilities:
Receivables from clients	(91,058)	(49,360)
Receivables from product sponsors, broker-dealers and clearing organizations	(17,680)	(4,454)
Advisor loans	(92,253)	(31,323)
Receivables from others	(10,377)	(18,103)
Securities owned	(15,446)	(1,347)
Securities borrowed	6,215	(11,096)
Other assets	(18,084)	6,305
Drafts payable	9,414	(45,473)
Payables to clients	(158,093)	(96,515)
Payables to broker-dealers and clearing organizations	98	(9,793)
Accrued commission and advisory expenses payable	21,081	4,656
Accounts payable and accrued liabilities	19,388	17,239
Income taxes receivable/payable	22,061	6,833
Unearned revenue	10,324	10,766
Securities sold, but not yet purchased	(850)	(48)
Net cash provided by operating activities	196,063	123,608
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(85,198)	(85,597)
Proceeds from disposal of fixed assets	0	12
Purchase of securities classified as held-to-maturity	(4,905)	(5,969)
Proceeds from maturity of securities classified as held-to-maturity	3,750	3,000
National Planning Holdings acquisition payment	0	(325,000)
Net cash used in investing activities	(86,353)	(413,554)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of senior secured term loans	(11,250)	(2,401,610)
Proceeds from senior secured term loans and senior notes	0	2,611,594
Payments of Debt Issuance Costs	0	(22,676)
Tax payments related to settlement of restricted stock units	(4,536)	(3,155)
Repurchase of common stock	(300,091)	(83,721)
Dividends on common stock	(66,847)	(67,765)
Proceeds from stock option exercises and other	43,248	77,876
Payment of Leasehold Financing Obligation	(2,461)	(1,337)
Net cash (used in) provided by financing activities	(341,937)	109,206
NET DECREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(232,227)	(180,740)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — Beginning of period	1,625,655
CASH, CASH EQUIVALENTS AND RESTRICTED CASH— End of period	1,393,428	1,377,868
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest paid	105,057	77,253
Income taxes paid	89,254	103,157
NONCASH DISCLOSURES:
Capital expenditures included in accounts payable and accrued liabilities	26,903	12,280
Finance and capital lease obligations	0	3,906
Debt issuance cost included in accounts payable and accrued liabilities	0	1,390
Discount on proceeds from senior secured credit facilities recorded as debt issuance cost	$ 0	$ 5,040

Condensed Consolidated Statem_8

Condensed Consolidated Statements of Cash Flows (Unaudited) cash, cash equivalent and restricted cash reconciliation - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2015
Supplemental Cash Flow Elements [Abstract]
Cash and Cash Equivalents, at Carrying Value	$ 768,546	$ 811,136	$ 577,961
Cash and Securities Segregated under Federal and Other Regulations	566,128	763,831	754,683
Restricted Cash and Cash Equivalents	58,754	50,688	45,224
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 1,393,428	$ 1,625,655	$ 1,377,868	$ 1,558,608

Organization and Description of

Organization and Description of the Company	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of the Company	Organization and Description of the Company LPL Financial Holdings Inc. (“LPLFH”), a Delaware holding corporation, together with its consolidated subsidiaries (collectively, the “Company”), provides an integrated platform of brokerage and investment advisory services to independent financial advisors and financial advisors at financial institutions (collectively “advisors”) in the United States. Through its custody and clearing platform, using both proprietary and third-party technology, the Company provides access to diversified financial products and services, enabling its advisors to offer independent financial advice and brokerage services to retail investors (their “clients”). Description of Subsidiaries LPL Holdings, Inc. (“LPLH”), a Massachusetts holding corporation, owns 100% of the issued and outstanding common stock or other ownership interest in each of LPL Financial LLC (“LPL Financial”), Fortigent Holdings Company, Inc., and LPL Insurance Associates, Inc. (“LPLIA”). LPLH is also the majority stockholder in PTC Holdings, Inc. (“PTCH”), and owns 100% of the issued and outstanding voting common stock. Each member of PTCH’s board of directors meets the direct equity ownership interest requirements that are required by the Office of the Comptroller of the Currency. The Company has established a wholly-owned series captive insurance entity that underwrites insurance for various legal and regulatory risks. LPL Financial, with primary offices in San Diego, California; Fort Mill, South Carolina; and Boston, Massachusetts, is a clearing broker-dealer and an investment advisor that principally transacts business as an agent for its advisors and financial institutions on behalf of their clients in a broad array of financial products and services. LPL Financial is licensed to operate in all 50 states, Washington D.C., Puerto Rico, and the U.S. Virgin Islands. Fortigent Holdings Company, Inc. and its subsidiaries (“Fortigent”) provide solutions and consulting services to registered investment advisors, banks, and trust companies serving high-net-worth clients. PTCH is a holding company for The Private Trust Company, N.A. (“PTC”). PTC is chartered as a non-depository limited purpose national bank, providing a wide range of trust, investment management oversight, and custodial services for estates and families. PTC also provides Individual Retirement Account custodial services for LPL Financial.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”), which require the Company to make estimates and assumptions regarding the valuation of certain financial instruments, intangible assets, allowance for doubtful accounts, share-based compensation, accruals for liabilities, income taxes, revenue and expense accruals, and other matters that affect the consolidated financial statements and related disclosures. The unaudited condensed consolidated financial statements reflect all adjustments which are, in the opinion of management, necessary to present fairly the results for the interim periods presented. Actual results could differ from those estimates under different assumptions or conditions and the differences may be material to the consolidated financial statements. The unaudited condensed consolidated financial statements do not include all information and notes necessary for a complete presentation of results of income, comprehensive income, financial position, and cash flows in conformity with GAAP. Accordingly, these financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the related notes for the year ended December 31, 2017 , contained in the Company’s Annual Report on Form 10-K, as amended by Amendment No. 1 on Form 10-K/A filed on February 27, 2018 (collectively, the "2017 Annual Report on Form 10-K"), as filed with the SEC. For the Company’s significant accounting policies affecting revenue from contracts with customers, see Note 3 . Revenues . A summary of other significant accounting policies are included in Note 2 . Summary of Significant Accounting Policies , in the Company’s audited consolidated financial statements and the related notes for the year ended December 31, 2017 . There have been no other significant changes to these accounting policies during the first nine months of 2018 . Consolidation These unaudited condensed consolidated financial statements include the accounts of LPLFH and its subsidiaries. Intercompany transactions and balances have been eliminated. Equity investments over which the Company exercises significant influence, but does not exercise control and is not the primary beneficiary are accounted for using the equity method. Reportable Segment Management has determined that the Company operates in one segment, given the similarities in economic characteristics between our operations and the common nature of our products and services, production and distribution processes, and regulatory environment. Cash and Cash Equivalents Cash equivalents are highly liquid investments with an original maturity of 90 days or less that are not required to be segregated under federal or other regulations. The Company's cash and cash equivalents are composed of interest and noninterest-bearing deposits, money market funds, and United States government obligations. Cash Segregated Under Federal and Other Regulations The Company's subsidiary, LPL Financial, is required to maintain cash or qualified securities in a segregated reserve account for the exclusive benefit of its customers in accordance with Rule 15c3-3 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and other regulations. Held within this account is approximately $100,000 for the proprietary accounts of introducing brokers. Restricted Cash Restricted cash primarily represents cash held by and for use by the Company’s captive insurance subsidiary. Fair Value of Financial Instruments The Company’s financial assets and liabilities are carried at fair value or at amounts that, because of their short-term nature, approximate current fair value, with the exception of its held-to-maturity securities and indebtedness, which the Company carries at amortized cost. The Company measures the implied fair value of its debt instruments using trading levels obtained from a third-party service provider. Accordingly, the debt instruments qualify as Level 2 fair value measurements. See Note 5 . Fair Value Measurements , for additional detail regarding the Company’s fair value measurements. As of September 30, 2018 , the carrying amount and fair value of the Company’s indebtedness was approximately $2,385.0 million and $2,371.7 million , respectively. As of December 31, 2017 , the carrying amount and fair value was approximately $2,396.3 million and $2,422.0 million , respectively. Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases , which establishes a right-of-use model that requires a lessee to record a right-of-use asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the statement of operations. In July 2018, the FASB issued ASU 2018-11, Leases – Targeted Improvements, which provides an optional transition method that allows entities to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company expects to adopt the provisions of this guidance, including the optional transition method, on January 1, 2019. The right of use asset and corresponding lease liability for these leases will be recognized on the Company's balance sheet upon adoption. The Company is evaluating the impact that ASU 2016-02 will have on its related disclosures. In June 2018, FASB issued ASU 2018-07, Stock Compensation (Topic 718): Improvements to Non-employee Share-Based Payment Accounting, which expands the scope of Topic 718 to include share-based payments granted to non-employees. Consistent with the requirement for employee share-based payment awards, non-employee share-based payment awards within the scope of Topic 718 will be measured at grant-date fair value of the equity instruments. The Company expects to adopt the provisions of this guidance on January 1, 2019, and is evaluating the impact of ASU 2018-07 on advisor and financial institution equity awards in the consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement . ASU 2018-13 removes or modifies certain current disclosures, and adds additional disclosures. The changes are meant to provide more relevant information regarding valuation techniques and inputs used to arrive at measures of fair value, uncertainty in the fair value measurements, and how changes in fair value measurements impact an entity's performance and cash flows. Certain disclosures in ASU 2018-13 will need to be applied on a retrospective basis and others on a prospective basis. Early adoption is permitted. The Company expects to adopt the provisions of this guidance on January 1, 2020, and is currently evaluating the impact that ASU 2018-13 will have on its related disclosures. Recently Adopted Accounting Pronouncements In May 2014, FASB issued ASU 2014-09, Revenue from Contracts with Customers: Topic 606 , to supersede nearly all existing revenue recognition guidance under GAAP. ASU 2014-09 also requires new qualitative and quantitative disclosures, including disaggregation of revenues and descriptions of performance obligations. The Company adopted the provisions of this guidance on January 1, 2018 using the modified retrospective approach. The Company has performed an assessment of its revenue contracts as well as worked with industry participants on matters of interpretation and application and has not identified any material changes to the timing or amount of its revenue recognition under ASU 2014-09. The Company's accounting policies did not change materially as a result of applying the principles of revenue recognition from ASU 2014-09 and are largely consistent with existing guidance and current practices applied by the Company. Refer to Note 3 . Revenues , for additional disaggregation of revenue in accordance with ASU 2014-09. In August 2016, the FASB issued ASU 2016-15, Statements of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments , which clarifies how companies present and classify certain cash receipts and cash payments in the statement of cash flows. The Company adopted the provisions of this guidance on January 1, 2018 and the adoption had no impact on its consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statements of Cash Flows (Topic 230): Classification and Presentation of Restricted Cash in the Statements of Cash Flows, which requires that restricted cash and restricted cash equivalents be included as components of total cash and cash equivalents in the statement of cash flows. The Company adopted the provisions of this guidance on January 1, 2018, and began presenting cash segregated for regulatory purposes and restricted cash activity as a component of cash and cash equivalent on the consolidated statements of cash flows using a retrospective transition method for each period presented. In May 2017, the FASB issued ASU No. 2017-09, Scope of Modification Accounting (Topic 718)

Revenue

Revenue	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenues	Revenues Adoption of ASC Topic 606, Revenue from Contracts with Customers On January 1, 2018, the Company adopted ASC Topic 606, Revenue from Contracts with Customers (“Topic 606”) using the modified retrospective method applied to those contracts which were not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under Topic 606, while prior period amounts are not adjusted and continue to be reported in accordance with our historic accounting under Topic 605. There was no impact to retained earnings as of January 1, 2018, or to revenue for the three and nine months ended September 30, 2018 , after adopting Topic 606, as revenue recognition and timing of revenue did not change as a result of implementing Topic 606. Revenue Recognition Revenues are recognized when control of the promised services is transferred to customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those services. Revenues are analyzed to determine whether the Company is the principal (i.e., reports revenues on a gross basis) or agent (i.e., reports revenues on a net basis) in the contract. Principal or agent designations depend primarily on the control an entity has over the product or service before control is transferred to a customer. The indicators of which party exercises control include primary responsibility over performance obligations, inventory risk before the good or service is transferred and discretion in establishing the price. Commission Revenue Commission revenue represents sales commissions generated by advisors for their clients’ purchases and sales of securities on exchanges and over-the-counter, as well as purchases of other investment products. The Company views the selling, distribution and marketing, or any combination thereof, of investment products to such clients as a single performance obligation to the product sponsors. The Company is the principal for commission revenue, as it is responsible for the execution of the clients’ purchases and sales, and maintains relationships with the product sponsors. Advisors assist the Company in performing its obligations. Accordingly, total commission revenues are reported on a gross basis. The following table presents our total commission revenue disaggregated by investment product category (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Variable annuities $ 201,075 $ 163,778 $ 597,613 $ 498,027 Mutual funds 155,579 131,339 470,665 397,323 Alternative investments 6,331 6,676 18,602 20,565 Fixed annuities 47,117 32,764 127,288 109,236 Equities 19,082 17,748 62,071 58,520 Fixed income 32,144 23,912 93,368 77,664 Insurance 16,155 17,338 51,993 51,355 Group annuities 9,064 9,319 27,576 31,799 Other 328 137 595 392 Total commission revenue $ 486,875 $ 403,011 $ 1,449,771 $ 1,244,881 The Company generates two types of commission revenue: sales-based commission revenue that is recognized at the point of sale on the trade date and trailing commission revenue that is recognized over time as earned. Sales-based commission revenue varies by investment product and is based on a percentage of an investment product's current market value at the time of purchase. Trailing commission revenue is generally based on a percentage of the current market value of clients' investment holdings in trail-eligible assets, and is recognized over the period during which services, such as on-going support, are performed. As trailing commission revenue is based on the market value of clients' investment holdings, this variable consideration is constrained until the market value is determinable. The following table presents our sales-based and trailing commission revenues disaggregated by product category (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Sales-based Variable annuities $ 57,491 $ 46,148 $ 168,487 $ 150,103 Mutual funds 33,319 30,638 107,910 102,009 Alternative investments 1,822 2,550 5,457 11,348 Fixed annuities 40,040 27,906 107,709 94,930 Equities 19,082 17,748 62,071 58,520 Fixed income 25,757 17,967 74,587 60,371 Insurance 14,433 15,906 46,877 46,914 Group annuities 1,273 1,098 3,615 3,929 Other 328 137 595 392 Total sales-based revenue $ 193,545 $ 160,098 $ 577,308 $ 528,516 Trailing Variable annuities $ 143,584 $ 117,630 $ 429,126 $ 347,924 Mutual funds 122,260 100,701 362,755 295,314 Alternative investments 4,509 4,126 13,145 9,217 Fixed annuities 7,077 4,858 19,579 14,306 Fixed income 6,387 5,945 18,781 17,293 Insurance 1,722 1,432 5,116 4,441 Group annuities 7,791 8,221 23,961 27,870 Total trailing revenue $ 293,330 $ 242,913 $ 872,463 $ 716,365 Total commission revenue $ 486,875 $ 403,011 $ 1,449,771 $ 1,244,881 Advisory Revenue Advisory revenue represents fees charged to advisors' clients' accounts on the Company's corporate advisory platform. The Company provides ongoing investment advice and acts as a custodian, providing brokerage and execution services on transactions, and performs administrative services for these accounts. This series of performance obligations transfers control of the services to the client over time as the services are performed. This revenue is recognized ratably over time to match the continued delivery of the performance obligations to the client over the life of the contract. The advisory revenue generated from the Company's corporate advisory platform is based on a percentage of the market value of the eligible assets in the clients' advisory accounts. As such, the consideration for this revenue is variable and an estimate of the variable consideration is constrained due to dependence on unpredictable market impacts on client portfolio values. The constraint is removed once the portfolio value can be determined. The Company provides advisory services to clients on its corporate advisory platform through the advisor. The Company is the principal in these arrangements and recognizes advisory revenue on a gross basis, as the Company is responsible for satisfying the performance obligations, carries the inventory risk and has control over determining the fees. Advisors assist the Company in performing its obligations. Asset-Based Revenue Asset-based revenue is comprised of fees from the Company's cash sweep program, which consists of fees from its money market cash sweep vehicle and other cash sweep vehicles, sponsorship programs, and recordkeeping. Money Market Cash Sweep Fees Money market cash sweep fees are generated based on balances in advisors’ clients’ money market cash sweep accounts. Uninvested cash balances in the advisors’ clients' accounts are swept into third-party money market funds for which the Company receives fees for administration and recordkeeping, which are based on account type and the invested balances. These fees are paid and recognized over time. The Company is principal in these arrangements and recognizes revenue from money market cash sweep fees on a gross basis as it is primarily responsible for the administration and recordkeeping. Sponsorship Programs The Company receives fees from product sponsors, primarily mutual fund and annuity companies, for marketing support and sales force education and training efforts. Compensation for these performance obligations is generally calculated as a fixed fee, or as a percentage of the average annual amount of product sponsor assets held in advisors' clients' accounts, or as a percentage of new sales, or a combination. As the value of product sponsor assets held in advisor's clients' accounts is susceptible to unpredictable market changes, this revenue includes variable consideration and is constrained until the date that the fees are determinable. The Company is the principal in these arrangements as it is responsible for and determines the level of servicing and marketing support it provides to the product sponsors. Recordkeeping The Company generates this revenue by providing recordkeeping, account maintenance, reporting and other related services to product sponsors. This includes revenue from omnibus processing in which the Company establishes and maintains sub-account records for its clients to reflect the purchase, exchange and redemption of mutual fund shares, and consolidates clients' trades within a mutual fund. Omnibus processing fees are paid to the Company by the mutual fund or its affiliates and are based on the value of mutual fund assets in accounts for which the Company provides omnibus processing services and the number of accounts in which the related mutual fund positions are held. Recordkeeping revenue also includes revenues from networking recordkeeping services. Networking revenues on brokerage assets are correlated to the number of positions or value of assets that the Company administers and are paid by mutual fund and annuity product manufacturers. These recordkeeping revenues are recognized over time as the Company fulfills its performance obligations. As recordkeeping fees are susceptible to unpredictable market changes that influence market value and fund positions, these revenues include variable consideration and are constrained until the date that the fees are determinable, such as the last date of the contract period in which the market value of the respective product sponsor assets for the period is available. Depending on the contract, the Company is both principal and agent for recordkeeping revenue. In instances for which the Company is providing these services to financial product manufacturers on behalf of third parties and does not have ultimate control of the service before transfer to the customer, the Company is considered to be an agent and reports these revenues on a net basis. In other cases, where the Company uses a sub-contractor to provide these services and is responsible for unperformed services, the Company is considered principal and reports these revenues on a gross basis. The following table sets forth asset-based revenue at a disaggregated level (dollars in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Asset-based revenue Money market cash sweep fees $ 5,762 $ 4,199 $ 15,576 $ 15,645 Other cash sweep vehicles fees (1) 121,412 77,418 337,068 197,470 Total cash sweep revenue 127,174 81,617 352,644 213,115 Sponsorship programs 58,065 48,292 168,074 143,458 Recordkeeping 63,656 54,044 186,116 158,053 Total asset-based revenue $ 248,895 $ 183,953 $ 706,834 $ 514,626 (1) Revenues from the Company's other cash sweep vehicles are not in scope for Topic 606 because such revenues are generated pursuant to contracts with depository banks. In these vehicles, cash balances in the advisors' clients’ accounts are swept into the Company's insured sweep vehicles at depository banks. Clients earn interest for their balances on deposit and the Company earns a fee based on prevailing interest rates or per account. Transaction and Fee Revenue Transaction revenue primarily includes fees the Company charges to advisors and their clients for executing certain transactions in brokerage and fee-based advisory accounts. Transaction revenue is recognized at the point-in-time that a transaction is executed, which is generally the trade-date. Fee revenue may be generated from advisors or their clients. Fee revenues primarily include IRA custodian fees, contract and licensing fees, and other client account fees. In addition, the Company hosts certain advisor conferences that serve as training, education, sales, and marketing events, for which a fee is charged for attendance. Fee revenue is recognized when the Company satisfies its performance obligations. Recognition varies from point-in-time to over time depending on whether the service is provided once at an identifiable point-in-time or if the service is provided continually over the contract life. The following table sets forth transaction and fee revenue disaggregated by recognition pattern (dollars in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Transaction and Fee Revenue Point-in-time (1) $ 78,465 $ 66,244 $ 240,954 $ 213,182 Over time (2) 40,476 37,755 111,091 108,340 Total transaction and fee revenue 118,941 103,999 352,045 321,522 (1) Transaction and fee revenue recognized point-in-time includes revenue such as transaction fees, IRA termination fees, and IRA custodian fees. (2) Transaction and fee revenue recognized over time includes revenue such as error and omission insurance fees, licensing fees, and conference service fees. The Company is the principal and recognizes transaction and fee revenue on a gross basis as it is primarily responsible for delivering the respective services being provided, which is demonstrated by the Company's ability to control the fee amounts charged to customers. Interest Income The Company earns interest income from client margin accounts and cash equivalents, net of operating expense. This revenue is not in scope for Topic 606 as it is not generated from contracts with customers. Other Revenue Other revenue primarily includes mark-to-market gains and losses on assets held by the Company for its advisor non-qualified deferred compensation plan and model research portfolios, marketing allowances received from certain financial product manufacturers, primarily those who offer alternative investments, such as non-traded real estate investment trusts and business development companies, and other miscellaneous revenues. These revenues are not in scope for Topic 606 as they are not generated from contracts with customers. Arrangement with Multiple Performance Obligations The Company's contracts with customers may include multiple performance obligations. Contracts with customers that include multiple performance obligations have performance obligations that follow the same revenue recognition pattern and are recorded in the same financial statement line item. Unearned Revenue We record unearned revenue when cash payments are received or due in advance of our performance obligations, including amounts which are refundable. The increase in the unearned revenue balance for the nine months ended September 30, 2018 is primarily driven by cash payments received or due in advance of satisfying our performance obligations, offset by $71.3 million of revenues recognized that were included in the unearned revenue balance as of December 31, 2017. The Company receives cash revenues for advisory services not yet performed and conferences not yet held. For advisory services, revenue is recognized as the Company provides the administration, brokerage and execution services over time to satisfy the performance obligations. For conference revenue, the Company recognizes this revenue as the conferences are held. Practical Expedients and Exemptions The Company has applied Topic 606’s practical expedient that permits for the non-disclosure of the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less and (ii) contracts for which the Company recognizes revenue at the amount to which it has the right to invoice for services performed.

Acquisitions Acquisitions

Acquisitions Acquisitions	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Acquisitions	Acquisitions National Planning Holdings, Inc. On August 15, 2017, the Company entered into an asset purchase agreement (“Asset Purchase Agreement”) with National Planning Holdings, Inc. (“NPH”), and its four broker-dealer subsidiaries (collectively with NPH, “NPH Sellers”) to acquire certain assets and rights of the NPH Sellers, including business relationships with financial advisors who become affiliated with the Company. In accordance with ASC 805, Business Combinations, control transferred when the Company onboarded NPH advisors and client assets onto its platform, which occurred in two waves. The first wave was completed in the fourth quarter of 2017 and the second wave was completed in the first quarter of 2018 (the "Conversion Period"). The Company paid $325 million to the NPH Sellers at closing, which occurred on August 15, 2017 and was included in the National Planning Holdings acquisition line on the unaudited condensed consolidated statements of financial condition. The Company recorded intangible assets of $98.4 million in advisor relationships and $61.9 million in goodwill in the fourth quarter of 2017, following the completion of wave one and intangible assets of $112.7 million in advisor relationships and $49.0 million

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date under current market conditions. Inputs used to measure fair value are prioritized within a three-level fair value hierarchy. This hierarchy requires entities to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1 — Quoted prices in active markets for identical assets or liabilities. Level 2 — Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data. Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. This includes certain pricing models, discounted cash flow methodologies, and similar techniques that use significant unobservable inputs. There have been no transfers of assets or liabilities between these fair value measurement classifications during the nine months ended September 30, 2018 . The Company’s fair value measurements are evaluated within the fair value hierarchy, based on the nature of inputs used to determine the fair value at the measurement date. At September 30, 2018 , the Company had the following financial assets and liabilities that are measured at fair value on a recurring basis: Cash Equivalents — The Company’s cash equivalents include money market funds, which are short term in nature with readily determinable values derived from active markets. Securities Owned and Securities Sold, But Not Yet Purchased — The Company’s trading securities consist of house account model portfolios established and managed for the purpose of benchmarking the performance of its fee-based advisory platforms and temporary positions resulting from the processing of client transactions. Examples of these securities include money market funds, U.S. treasury obligations, mutual funds, certificates of deposit, and traded equity and debt securities. The Company uses prices obtained from independent third-party pricing services to measure the fair value of its trading securities. Prices received from the pricing services are validated using various methods including comparison to prices received from additional pricing services, comparison to available quoted market prices, and review of other relevant market data including implied yields of major categories of securities. In general, these quoted prices are derived from active markets for identical assets or liabilities. When quoted prices in active markets for identical assets and liabilities are not available, the quoted prices are based on similar assets and liabilities or inputs other than the quoted prices that are observable, either directly or indirectly. For certificates of deposit and treasury securities, the Company utilizes market-based inputs, including observable market interest rates that correspond to the remaining maturities or the next interest reset dates. At September 30, 2018 , the Company did not adjust prices received from the independent third-party pricing services. Other Assets — The Company’s other assets include: (1) deferred compensation plan assets that are invested in money market and other mutual funds, which are actively traded and valued based on quoted market prices; and (2) certain non-traded real estate investment trusts and auction rate notes, which are valued using quoted prices for identical or similar securities and other inputs that are observable or can be corroborated by observable market data. The following table summarizes the Company’s financial assets and financial liabilities measured at fair value on a recurring basis at September 30, 2018 (in thousands): Level 1 Level 2 Level 3 Total Assets Cash equivalents $ 85,721 $ — $ — $ 85,721 Securities owned — trading: Money market funds 169 — — 169 Mutual funds 9,966 — — 9,966 Equity securities 2,726 — — 2,726 Debt securities — 1 — 1 U.S. treasury obligations 19,593 — — 19,593 Total securities owned — trading 32,454 1 — 32,455 Other assets 204,004 8,606 — 212,610 Total assets at fair value $ 322,179 $ 8,607 $ — $ 330,786 Liabilities Equity securities $ 175 $ — $ — $ 175 Debt securities — 158 — 158 Total securities sold, but not yet purchased 175 158 — 333 Total liabilities at fair value $ 175 $ 158 $ — $ 333 The following table summarizes the Company’s financial assets and financial liabilities measured at fair value on a recurring basis at December 31, 2017 (in thousands): Level 1 Level 2 Level 3 Total Assets Cash equivalents $ 147,034 $ — $ — $ 147,034 Securities owned — trading: Money market funds 288 — — 288 Mutual funds 10,850 — — 10,850 Equity securities 201 — — 201 Debt securities — 60 — 60 U.S. treasury obligations 6,480 — — 6,480 Total securities owned — trading 17,819 60 — 17,879 Other assets 180,377 9,282 — 189,659 Total assets at fair value $ 345,230 $ 9,342 $ — $ 354,572 Liabilities Securities sold, but not yet purchased: Mutual funds $ 3 $ — $ — $ 3 Equity securities 67 — — 67 Debt securities — 1,112 — 1,112 Total securities sold, but not yet purchased 70 1,112 — 1,182 Total liabilities at fair value $ 70 $ 1,112 $ — $ 1,182

Held-to-Maturity Securities

Held-to-Maturity Securities	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Held-to-Maturity Securities	Held-to-Maturity Securities The Company holds certain investments in securities, primarily U.S. government notes, which are recorded at amortized cost because the Company has both the intent and the ability to hold these investments to maturity. Interest income is accrued as earned. Premiums and discounts are amortized using a method that approximates the effective yield method over the term of the security and are recorded as an adjustment to the investment yield. The amortized cost, gross unrealized loss, and fair value of securities held-to-maturity were as follows (in thousands): September 30, December 31, Amortized cost $ 13,005 $ 11,833 Gross unrealized loss (123 ) (86 ) Fair value $ 12,882 $ 11,747 At September 30, 2018 , the securities held-to-maturity were scheduled to mature as follows (in thousands): Within one year After one but within five years After five but within ten years Total U.S. government notes — at amortized cost $ 4,995 $ 8,010 $ — $ 13,005 U.S. government notes — at fair value $ 4,961 $ 7,921 $ — $ 12,882

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets A summary of the activity in goodwill is presented below (in thousands): Balance at December 31, 2016 $ 1,365,838 Goodwill acquired 61,931 Balance at December 31, 2017 $ 1,427,769 Goodwill acquired 49,006 Balance at September 30, 2018 $ 1,476,775 The components of intangible assets were as follows at September 30, 2018 (dollars in thousands): Weighted-Average Life Remaining (in years) Gross Carrying Value Accumulated Amortization Net Carrying Value Definite-lived intangible assets: Advisor and financial institution relationships 7.3 $ 651,642 $ (303,823 ) $ 347,819 Product sponsor relationships 7.4 234,086 (146,547 ) 87,539 Client relationships 6.2 19,133 (12,506 ) 6,627 Trade names 3.6 1,200 (770 ) 430 Total definite-lived intangible assets $ 906,061 $ (463,646 ) $ 442,415 Indefinite-lived intangible assets: Trademark and trade name 39,819 Total intangible assets $ 482,234 The components of intangible assets were as follows at December 31, 2017 (dollars in thousands): Weighted-Average Life Remaining (in years) Gross Carrying Value Accumulated Amortization Net Carrying Value Definite-lived intangible assets: Advisor and financial institution relationships 8.0 $ 538,921 $ (269,294 ) $ 269,627 Product sponsor relationships 8.1 234,086 (137,615 ) 96,471 Client relationships 6.8 19,133 (11,477 ) 7,656 Trade names 4.3 1,200 (680 ) 520 Total definite-lived intangible assets $ 793,340 $ (419,066 ) $ 374,274 Indefinite-lived intangible assets: Trademark and trade name 39,819 Total intangible assets $ 414,093 Total amortization of intangible assets was $15.7 million and $9.4 million for the three months ended September 30, 2018 and 2017 , respectively, and $44.6 million and $28.3 million for the nine months ended September 30, 2018 and 2017 , respectively. Future amortization expense is estimated as follows (in thousands): 2018 - remainder $ 15,673 2019 62,688 2020 62,297 2021 62,140 2022 61,340 Thereafter 178,277 Total $ 442,415

Debt

Debt	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt	Debt On September 21, 2017, LPLFH and LPLH entered into a second amendment (the “Amendment”) to its amended and restated credit agreement, dated March 10, 2017 (as amended by that certain amendment agreement, dated as of June 20, 2017, the Amendment, and as further amended to date, the “Credit Agreement”), and repriced its existing $500.0 million senior secured revolving credit facility and $1,695.8 million senior secured Term Loan B facility. Additionally, LPLH raised $400.0 million in aggregate principal amount of notes (the “Additional Notes”), which were issued above par at 103.0% as an add-on to the Original Notes (as defined below). On March 10, 2017, LPLFH and LPLH entered into a fourth amendment agreement, which amended and restated LPLH’s then-existing credit agreement and refinanced LPLH’s then-outstanding senior secured credit facilities. The proceeds of the new Term Loan B, together with the proceeds from the offering of $500.0 million aggregate principal amount of 5.75% senior notes (the “Original Notes” and, together with the Additional Notes, the “Notes”) and cash, were used to repay LPLH’s then-existing senior secured credit facilities and to pay accrued interest and related fees and expenses. Issuance of 5.75% Senior Notes due 2025 The Original Notes were issued in March 2017 pursuant to an Indenture, dated March 10, 2017, among LPLH, U.S. Bank National Association, as trustee, and certain of the Company’s subsidiaries as guarantors (“Indenture”). The Additional Notes were issued in September 2017 pursuant to a Supplemental Indenture, dated September 21, 2017, among LPLH, U.S. Bank National Association, as trustee, and certain of the Company’s subsidiaries as guarantors. The Notes are unsecured obligations that will mature on September 15, 2025, and bear interest at the rate of 5.75% per year, with interest payable semi-annually, beginning on September 15, 2017 with respect to the Additional Notes. The Company may redeem all or part of the Notes at any time prior to March 15, 2020 (subject to a customary “equity claw” redemption right) at 100% of the principal amount redeemed plus a “make-whole” premium. Thereafter the Company may redeem all or part of the Notes at annually declining redemption premiums until March 15, 2023, at and after which date the redemption price will be equal to 100% of the principal amount redeemed. Senior Secured Credit Facilities Borrowings under the Term Loan B facility bear interest at a rate per annum of 225 basis points over the Eurodollar Rate or 125 basis points over the base rate (as defined in the Credit Agreement), and have no leverage or interest coverage maintenance covenants. Borrowings under the revolving credit facility bear interest at a rate per annum ranging from 125 to 175 basis points over the Eurodollar Rate or 25 to 75 basis points over the base rate, depending on the Consolidated Secured Debt to Consolidated EBITDA Ratio (as defined in the Credit Agreement). The Eurodollar Rate option is the one-, two-, three-, or six-month LIBOR rate, as selected by LPLH, or, with the approval of the applicable lenders, twelve month LIBOR rate or the LIBOR rate for another period acceptable to the Administrative Agent (including a shorter period). The Eurodollar Rate is subject to an interest rate floor of 0% . The Company’s outstanding long-term borrowings as of the dates below were as follows (dollars in thousands): September 30, 2018 December 31, 2017 Long-Term Borrowings Balance Applicable Margin Interest Rate Balance Applicable Margin Interest rate Maturity Revolving Credit Facility $ — LIBOR+125bps — % $ — LIBOR+125bps — % 9/21/2022 Senior Secured Term Loan B (1) 1,485,000 LIBOR+225 bps 4.42 % 1,496,250 LIBOR+225 bps 3.81 % 9/21/2024 Senior Unsecured Notes (1)(2) 900,000 Fixed Rate 5.75 % 900,000 Fixed Rate 5.75 % 9/15/2025 Total long-term borrowings 2,385,000 2,396,250 Plus: Unamortized Premium 10,458 11,584 Less: Unamortized Debt Issuance Cost (20,345 ) (22,812 ) Net Carrying Value $ 2,375,113 $ 2,385,022 _____________________ (1) No leverage or interest coverage maintenance covenants. (2) The Senior Unsecured Notes were issued in two separate transactions; $500.0 million in Original Notes were issued in March 2017 at par; $400.0 million in Additional Notes were issued in September 2017 and priced at 103.0% of the aggregate principal amount. The Company is required to make quarterly amortization payments on the Term Loan B facility (commencing with the fiscal quarter ending December 31, 2017), each equal to 0.25% of the original principal amount of the loans under the Term Loan B facility. Voluntary prepayments of the Term Loan B facility may be made at any time without premium or penalty. As of September 30, 2018 , LPLH also had $10.6 million of irrevocable letters of credit, with an applicable interest rate margin of 1.25% , which were supported by the Company’s revolving credit facility. The Credit Agreement subjects the Company to certain non-financial covenants for the benefit of the revolving credit facility and Term Loan B facility. As of September 30, 2018 , the Company was in compliance with such covenants. Bank Loans Payable The Company maintains three uncommitted lines of credit. Two of the lines have unspecified limits, which are primarily dependent on the Company’s ability to provide sufficient collateral. The third line has a $200 million limit, and allows for both collateralized and uncollateralized borrowings. The lines were not utilized during the three months ended September 30, 2018 . The Company drew $160 million on one of the lines of credit at an interest rate of 2.99% during the nine months ended September 30, 2018 . There were no balances outstanding at September 30, 2018 or December 31, 2017

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases The Company leases office space and equipment under various operating leases. These leases are generally subject to scheduled base rent and maintenance cost increases, which are recognized on a straight-line basis over the period of the leases. Total rental expense for all operating leases was approximately $4.8 million and $4.8 million for the three months ended September 30, 2018 and 2017 , respectively, and $14.3 million and $15.3 million for the nine months ended September 30, 2018 and 2017 , respectively. Service and Development Contracts The Company is party to certain long-term contracts for systems and services that enable back office trade processing and clearing for its product and service offerings. Guarantees The Company occasionally enters into certain types of contracts that contingently require it to indemnify certain parties against third-party claims. The terms of these obligations vary and, because a maximum obligation is not explicitly stated, the Company has determined that it is not possible to make an estimate of the amount that it could be obligated to pay under such contracts. The Company’s subsidiary, LPL Financial, provides guarantees to securities clearing houses and exchanges under their standard membership agreements, which require a member to guarantee the performance of other members. Under these agreements, if a member becomes unable to satisfy its obligations to the clearing houses and exchanges, all other members would be required to meet any shortfall. The Company’s liability under these arrangements is not quantifiable and may exceed the cash and securities it has posted as collateral. However, the potential requirement for the Company to make payments under these agreements is remote. Accordingly, no liability has been recognized for these transactions. Loan Commitments From time to time, LPL Financial makes loans to its advisors, primarily to newly recruited advisors to assist in the transition process, which may be forgivable. Due to timing differences, LPL Financial may make commitments to issue such loans prior to actually funding them. These commitments are generally contingent upon certain events occurring, including but not limited to the advisor joining LPL Financial. LPL Financial had no significant unfunded commitments at September 30, 2018 . Legal & Regulatory Matters The Company is subject to extensive regulation and supervision by United States federal and state agencies and various self-regulatory organizations. The Company and its advisors periodically engage with such agencies and organizations, in the context of examinations or otherwise, to respond to inquiries, informational requests, and investigations. From time to time, such engagements result in regulatory complaints or other matters, the resolution of which has in the past and may in the future include fines, customer restitution and other remediation. Assessing the probability of a loss occurring and the amount of any loss related to a legal proceeding or regulatory matter is inherently difficult. While the Company exercises significant and complex judgments to make certain estimates presented in its consolidated financial statements, there are particular uncertainties and complexities involved when assessing the potential outcomes of legal proceedings and regulatory matters. The Company’s assessment process considers a variety of factors and assumptions, which may include: the procedural status of the matter and any recent developments; prior experience and the experience of others in similar matters; the size and nature of potential exposures; available defenses; the progress of fact discovery; the opinions of counsel and experts; potential opportunities for settlement and the status of any settlement discussions; as well as the potential for insurance coverage and indemnification, if available. The Company monitors these factors and assumptions for new developments and re-assesses the likelihood that a loss will occur and the estimated range or amount of loss, if those amounts can be reasonably determined. The Company has established an accrual for those legal proceedings and regulatory matters for which a loss is both probable and the amount can be reasonably estimated. Many of these losses are covered by third-party insurance or self-insurance through the Company's captive insurance subsidiary, as discussed below. On May 1, 2018 the Company agreed to a settlement structure with the North American Securities Administrators Association related to the Company's historical compliance with certain state “blue sky” laws. The Company is in the process of entering into separate administrative orders with 53 jurisdictions, which would result in aggregate fines of approximately $26.4 million . As part of the settlement structure, the Company agreed to engage independent third party consultants to conduct a historical review of certain equity and fixed income securities transactions, as well as an operational review of its systems for complying with blue sky securities registration requirements. The Company also agreed to offer remediation to customers who purchased certain equity and fixed-income securities since October 2006. As of the date of this quarterly report, the Company expects to incur costs related to this matter over the next few years, and it expects the majority of these costs to be covered by its captive insurance subsidiary, which had adequate loss reserves as of September 30, 2018 . A putative class action lawsuit has been filed against the Company and certain of its executive officers in federal district court alleging certain misstatements and omissions related to the Company’s share repurchases and financial performance in late 2015. Third-Party Insurance The Company maintains third-party insurance coverage for certain potential legal proceedings, including those involving client claims. With respect to client claims, the estimated losses on many of the pending matters are less than the applicable deductibles of the insurance policies. Self-Insurance The Company has self-insurance for certain potential liabilities, including various errors and omissions liabilities, through a wholly-owned captive insurance subsidiary. Liabilities associated with the risks that are retained by the Company are not discounted and are estimated by considering, in part, historical claims experience, severity factors, and other actuarial assumptions. The estimated loss accruals for these potential liabilities could be significantly affected if future occurrences and claims differ from such assumptions and historical trends used to estimate these loss reserves. As of September 30, 2018 , self-insurance liabilities are included in accounts payable and accrued liabilities in the unaudited condensed consolidated statements of financial condition. Self-insurance related charges are included in other expenses in the unaudited condensed consolidated statements of income for the three and nine months ended September 30, 2018 . Other Commitments As of September 30, 2018 , the Company had approximately $293.5 million of client margin loans that were collateralized with securities having a fair value of approximately $410.9 million that the Company can re-pledge, loan, or sell. Of these securities, approximately $56.5 million were client-owned securities pledged to the Options Clearing Corporation as collateral to secure client obligations related to options positions. As of September 30, 2018 , there were no restrictions that materially limited the Company’s ability to re-pledge, loan, or sell the remaining $354.3 million of client collateral. Trading securities on the unaudited condensed consolidated statements of financial condition includes $4.7 million and $6.5 million pledged to clearing organizations at September 30, 2018 and December 31, 2017

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2018
Stockholders' Equity Note [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	Stockholders’ Equity Dividends The payment, timing, and amount of any dividends are subject to approval by the Company’s board of directors (“Board of Directors”) as well as certain limits under the Credit Agreement and the Indenture. Cash dividends per share of common stock and total cash dividends paid on a quarterly basis were as follows (in millions, except per share data): 2018 2017 Dividend per Share Total Cash Dividend Dividend per Share Total Cash Dividend First quarter $ 0.25 $ 22.6 $ 0.25 $ 22.6 Second quarter $ 0.25 $ 22.3 $ 0.25 $ 22.6 Third quarter $ 0.25 $ 21.9 $ 0.25 $ 22.5 Share Repurchases The Company engages in share repurchase programs, which are approved by the Board of Directors, pursuant to which the Company may repurchase its issued and outstanding shares of common stock from time to time. Repurchased shares are included in treasury stock on the unaudited condensed consolidated statements of financial condition. As of September 30, 2018 , the Company was authorized to purchase up to an additional $200.0 million of shares pursuant to share repurchase programs approved by the Board of Directors. The Company had the following activity under its approved share repurchase program (in millions, except share and per share data): 2018 Total Number of Shares Purchased Weighted-Average Price Paid Per Share Total Cost (1) First quarter 967,500 $ 62.84 $ 60.8 Second quarter 1,791,493 $ 65.20 $ 116.8 Third quarter 1,849,027 $ 66.24 $ 122.5 4,608,020 $ 65.12 $ 300.1 _________________________ (1) Included in the total cost of shares purchased is a commission fee of $0.02

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stockholders' Equity	Share-Based Compensation In November 2010, the Company adopted the 2010 Omnibus Equity Incentive Plan (as amended and restated in May 2015, the “2010 Plan”), which provides for the granting of stock options, warrants, restricted stock awards, restricted stock units, deferred stock units, performance stock units, and other equity-based compensation. Since its adoption, awards have only been made out of the 2010 Plan. As of September 30, 2018 , there were 20,055,945 shares authorized for grant under the 2010 Plan. There were 6,630,320 shares reserved for issuance upon exercise or conversion of outstanding awards granted, and 6,484,606 shares remaining available for future issuance, under the 2010 Plan as of September 30, 2018 . Stock Options and Warrants The following table presents the weighted-average assumptions used in the Black-Scholes valuation model by the Company in calculating the fair value of its employee and officer stock options granted during the nine months ended September 30, 2018 : Expected life (in years) 5.43 Expected stock price volatility 34.80 % Expected dividend yield 1.71 % Risk-free interest rate 2.66 % Fair value of options $ 19.86 The following table summarizes the Company’s stock option and warrant activity for the nine months ended September 30, 2018 : Number of Shares Weighted- Average Exercise Price Weighted-Average Remaining Contractual Term (Years) Aggregate Intrinsic Value (In thousands) Outstanding — December 31, 2017 4,866,499 $ 31.73 Granted 478,824 $ 65.55 Exercised (1,218,087 ) $ 33.95 Forfeited and Expired (208,091 ) $ 37.81 Outstanding — September 30, 2018 3,919,145 $ 34.85 5.79 $ 116,683 Exercisable — September 30, 2018 2,682,517 $ 31.07 4.54 $ 89,711 Exercisable and expected to vest — September 30, 2018 3,857,324 $ 34.50 5.73 $ 116,157 The following table summarizes information about outstanding stock options and warrants as of September 30, 2018 : Outstanding Exercisable Range of Exercise Prices Number of Shares Weighted- Average Exercise Price Weighted-Average Number of Shares Weighted- Average Exercise Price $18.01 - $25.00 1,305,007 $ 20.54 5.32 947,556 $ 20.72 $25.01 - $30.00 397,714 $ 28.95 3.75 395,640 $ 28.94 $30.01 - $35.00 706,538 $ 33.13 3.07 706,538 $ 33.13 $35.01 - $45.00 665,708 $ 39.62 8.24 224,812 $ 39.77 $45.01 - $55.00 405,955 $ 48.72 6.08 405,955 $ 48.72 $55.01 - $71.00 438,223 $ 65.55 9.41 2,016 $ 65.50 3,919,145 $ 34.85 5.79 2,682,517 $ 31.07 The Company recognized share-based compensation related to the vesting of stock options awarded to employees and officers of $2.5 million and $2.0 million during the three months ended September 30, 2018 and 2017 , respectively, and $6.5 million and $5.8 million during the nine months ended September 30, 2018 and 2017 , respectively. As of September 30, 2018 , total unrecognized compensation cost related to non-vested stock options granted to employees and officers was $9.4 million , which is expected to be recognized over a weighted-average period of 1.98 years. Restricted Stock and Stock Units The following summarizes the Company’s activity in its restricted stock awards and stock units, which include restricted stock units, deferred stock units, and performance stock units, for the nine months ended September 30, 2018 : Restricted Stock Awards Stock Units Number of Shares Weighted-Average Grant-Date Fair Value Number of Shares Weighted-Average Grant-Date Fair Value Nonvested — December 31, 2017 12,796 $ 39.73 957,123 $ 32.81 Granted 7,057 $ 70.26 333,061 $ 69.60 Vested (12,796 ) $ 39.73 (361,535 ) $ 34.41 Forfeited — $ — (69,881 ) $ 39.04 Nonvested — September 30, 2018 7,057 $ 70.26 858,768 $ 45.89 Expected to vest — September 30, 2018 7,057 $ 70.26 800,959 $ 44.78 The Company grants restricted stock awards and deferred stock units to its directors, restricted stock units to its employees and officers, and performance stock units to its officers. Restricted stock awards and stock units must vest or are subject to forfeiture; however, restricted stock awards are included in our shares outstanding upon grant and have the same dividend and voting rights as our common stock. The Company recognized $3.6 million and $2.7 million of share-based compensation related to the vesting of restricted stock awards and stock units during the three months ended September 30, 2018 and 2017 , respectively, and $10.6 million and $8.9 million during the nine months ended September 30, 2018 and 2017 , respectively. As of September 30, 2018 , total unrecognized compensation cost for restricted stock awards and stock units was $19.6 million , which is expected to be recognized over a weighted-average remaining period of 2.14 years. The Company also grants restricted stock units to its advisors and to financial institutions. The Company recognized share-based compensation of $1.0 million and $2.3 million related to the vesting of these awards during the three months ended September 30, 2018 and 2017 , respectively, and $5.5 million and $5.3 million during the nine months ended September 30, 2018 and 2017 , respectively. As of September 30, 2018 , total unrecognized compensation cost for restricted stock units granted to advisors and financial institutions was $5.8 million , which is expected to be recognized over a weighted-average remaining period of 1.79

Earnings per Share

Earnings per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings per Share	Earnings Per Share Basic earnings per share is computed by dividing net income available to common stockholders by the weighted-average number of shares of common stock outstanding during the period. The computation of diluted earnings per share is similar to the computation of basic earnings per share, except that the denominator is increased to include the number of additional shares of common stock that would have been outstanding if dilutive potential shares of common stock had been issued. The calculation of basic and diluted earnings per share is as follows (in thousands, except per share data): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Net income $ 106,865 $ 58,142 $ 319,161 $ 174,765 Basic weighted-average number of shares outstanding 87,426 89,967 88,841 90,029 Dilutive common share equivalents 2,452 2,075 2,606 1,998 Diluted weighted-average number of shares outstanding 89,878 92,042 91,447 92,027 Basic earnings per share $ 1.22 $ 0.65 $ 3.59 $ 1.94 Diluted earnings per share $ 1.19 $ 0.63 $ 3.49 $ 1.90 The computation of diluted earnings per share excludes stock options, warrants, and stock units that are anti-dilutive. For the three months ended September 30, 2018 and 2017 , stock options, warrants, and stock units representing common share equivalents of 439,156 shares and 1,168,772 shares, respectively, were anti-dilutive. For the nine months ended September 30, 2018 and 2017 , stock options, warrants, and restricted stock units representing common share equivalents of 377,583 shares and 2,098,029

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (H.R. 1), the tax reform bill (the "Tax Act"), was signed into law. The Tax Act provided a permanent reduction in the Company's federal corporate income tax rate from 35% to 21% effective January 1, 2018. The Company’s effective income tax rate differs from the federal corporate tax rate of 21.0% , primarily as a result of state taxes, settlement contingencies, tax credits and other permanent differences in tax deductibility of certain expenses. These items resulted in effective tax rates of 27.5% and 39.8% for the three months ended September 30, 2018 and 2017 , respectively, and 25.8% and 38.6% for the nine months ended September 30, 2018 and 2017 , respectively.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Company has related party transactions with certain beneficial owners of more than ten percent of the Company's outstanding common stock. Additionally, through its subsidiary LPL Financial, the Company provides services and charitable contributions to the LPL Financial Foundation, an organization that provides volunteer and financial support within the Company's local communities. The Company recognized revenue for services provided to these related parties of $1.0 million and $0.7 million during the three months ended September 30, 2018 and 2017 , respectively, and $2.6 million and $2.2 million during the nine months ended September 30, 2018 and 2017 , respectively. The Company incurred expenses for the services provided by these related parties of $0.6 million during the three months ended September 30, 2018 and there were no related party expenses for the same period in 2017. The Company incurred expenses for the services provided by these related parties of $1.8 million and $0.1 million during the nine months ended September 30, 2018 and 2017 , respectively. As of September 30, 2018 and 2017

Net Capital and Regulatory Requ

Net Capital and Regulatory Requirements	9 Months Ended
	Sep. 30, 2018
Brokers and Dealers [Abstract]
Net Capital and Regulatory Requirements	Net Capital and Regulatory Requirements The Company’s registered broker-dealer, LPL Financial, is subject to the SEC’s Net Capital Rule (Rule 15c3-1 under the Exchange Act), which requires the maintenance of minimum net capital. The net capital rules also provide that the broker-dealer's capital may not be withdrawn if resulting net capital would be less than minimum requirements. Additionally, certain withdrawals require the approval of the SEC and FINRA to the extent they exceed defined levels, even though such withdrawals would not cause net capital to be less than minimum requirements. Net capital and the related net capital requirement may fluctuate on a daily basis. LPL Financial is a clearing broker-dealer and had net capital of $166.1 million with a minimum net capital requirement of $8.5 million as of September 30, 2018 . The Company’s subsidiary, PTC, also operates in a highly regulated industry and is subject to various regulatory capital requirements. Failure to meet minimum capital requirements can initiate certain mandatory and possible additional discretionary actions by regulators that, if undertaken, could have substantial monetary and non-monetary impacts to PTC’s operations. As of September 30, 2018 and December 31, 2017

Financial Instruments with Off-

Financial Instruments with Off-Balance-Sheet Credit Risk and Concentrations of Credit Risk	9 Months Ended
	Sep. 30, 2018
Concentration Risk Credit Risk Financial Instruments Off Balance Sheet Risk [Abstract]
Financial Instruments with Off-Balance-Sheet Credit Risk and Concentrations of Credit Risk	Financial Instruments with Off-Balance-Sheet Credit Risk and Concentrations of Credit Risk LPL Financial’s client securities activities are transacted on either a cash or margin basis. In margin transactions, LPL Financial extends credit to the advisor’s client, subject to various regulatory and internal margin requirements, collateralized by cash or securities in the client’s account. As clients write options contracts or sell securities short, LPL Financial may incur losses if the clients do not fulfill their obligations and the collateral in the clients’ accounts is not sufficient to fully cover losses that clients may incur from these strategies. To control this risk, LPL Financial monitors margin levels daily and clients are required to deposit additional collateral, or reduce positions, when necessary. LPL Financial is obligated to settle transactions with brokers and other financial institutions even if its advisors’ clients fail to meet their obligation to LPL Financial. Clients are required to complete their transactions on the settlement date, generally two business days after the trade date. If clients do not fulfill their contractual obligations, LPL Financial may incur losses. In addition, the Company occasionally enters into certain types of contracts to fulfill its sale of when, as, and if issued securities. When, as, and if issued securities have been authorized but are contingent upon the actual issuance of the security. LPL Financial has established procedures to reduce this risk by generally requiring that clients deposit cash or securities into their account prior to placing an order.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2018
Subsequent Event [Abstract]
Subsequent Events [Text Block]	Subsequent Events On October 23, 2018 , the Board of Directors declared a cash dividend of $0.25 per share on the Company's outstanding common stock to be paid on November 26, 2018 to all stockholders of record on November 8, 2018

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents Cash equivalents are highly liquid investments with an original maturity of 90 days or less that are not required to be segregated under federal or other regulations. The Company's cash and cash equivalents are composed of interest and noninterest-bearing deposits, money market funds, and United States government obligations. Cash Segregated Under Federal and Other Regulations The Company's subsidiary, LPL Financial, is required to maintain cash or qualified securities in a segregated reserve account for the exclusive benefit of its customers in accordance with Rule 15c3-3 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and other regulations. Held within this account is approximately $100,000 for the proprietary accounts of introducing brokers. Restricted Cash
Consolidation	Consolidation These unaudited condensed consolidated financial statements include the accounts of LPLFH and its subsidiaries. Intercompany transactions and balances have been eliminated. Equity investments over which the Company exercises significant influence, but does not exercise control and is not the primary beneficiary are accounted for using the equity method.
Reportable Segment	Reportable Segment Management has determined that the Company operates in one
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company’s financial assets and liabilities are carried at fair value or at amounts that, because of their short-term nature, approximate current fair value, with the exception of its held-to-maturity securities and indebtedness, which the Company carries at amortized cost. The Company measures the implied fair value of its debt instruments using trading levels obtained from a third-party service provider. Accordingly, the debt instruments qualify as Level 2 fair value measurements. See Note 5 . Fair Value Measurements , for additional detail regarding the Company’s fair value measurements. As of September 30, 2018 , the carrying amount and fair value of the Company’s indebtedness was approximately $2,385.0 million and $2,371.7 million , respectively. As of December 31, 2017 , the carrying amount and fair value was approximately $2,396.3 million and $2,422.0 million
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases , which establishes a right-of-use model that requires a lessee to record a right-of-use asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the statement of operations. In July 2018, the FASB issued ASU 2018-11, Leases – Targeted Improvements, which provides an optional transition method that allows entities to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company expects to adopt the provisions of this guidance, including the optional transition method, on January 1, 2019. The right of use asset and corresponding lease liability for these leases will be recognized on the Company's balance sheet upon adoption. The Company is evaluating the impact that ASU 2016-02 will have on its related disclosures. In June 2018, FASB issued ASU 2018-07, Stock Compensation (Topic 718): Improvements to Non-employee Share-Based Payment Accounting, which expands the scope of Topic 718 to include share-based payments granted to non-employees. Consistent with the requirement for employee share-based payment awards, non-employee share-based payment awards within the scope of Topic 718 will be measured at grant-date fair value of the equity instruments. The Company expects to adopt the provisions of this guidance on January 1, 2019, and is evaluating the impact of ASU 2018-07 on advisor and financial institution equity awards in the consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement . ASU 2018-13 removes or modifies certain current disclosures, and adds additional disclosures. The changes are meant to provide more relevant information regarding valuation techniques and inputs used to arrive at measures of fair value, uncertainty in the fair value measurements, and how changes in fair value measurements impact an entity's performance and cash flows. Certain disclosures in ASU 2018-13 will need to be applied on a retrospective basis and others on a prospective basis. Early adoption is permitted. The Company expects to adopt the provisions of this guidance on January 1, 2020, and is currently evaluating the impact that ASU 2018-13 will have on its related disclosures. Recently Adopted Accounting Pronouncements In May 2014, FASB issued ASU 2014-09, Revenue from Contracts with Customers: Topic 606 , to supersede nearly all existing revenue recognition guidance under GAAP. ASU 2014-09 also requires new qualitative and quantitative disclosures, including disaggregation of revenues and descriptions of performance obligations. The Company adopted the provisions of this guidance on January 1, 2018 using the modified retrospective approach. The Company has performed an assessment of its revenue contracts as well as worked with industry participants on matters of interpretation and application and has not identified any material changes to the timing or amount of its revenue recognition under ASU 2014-09. The Company's accounting policies did not change materially as a result of applying the principles of revenue recognition from ASU 2014-09 and are largely consistent with existing guidance and current practices applied by the Company. Refer to Note 3 . Revenues , for additional disaggregation of revenue in accordance with ASU 2014-09. In August 2016, the FASB issued ASU 2016-15, Statements of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments , which clarifies how companies present and classify certain cash receipts and cash payments in the statement of cash flows. The Company adopted the provisions of this guidance on January 1, 2018 and the adoption had no impact on its consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statements of Cash Flows (Topic 230): Classification and Presentation of Restricted Cash in the Statements of Cash Flows, which requires that restricted cash and restricted cash equivalents be included as components of total cash and cash equivalents in the statement of cash flows. The Company adopted the provisions of this guidance on January 1, 2018, and began presenting cash segregated for regulatory purposes and restricted cash activity as a component of cash and cash equivalent on the consolidated statements of cash flows using a retrospective transition method for each period presented. In May 2017, the FASB issued ASU No. 2017-09, Scope of Modification Accounting (Topic 718)

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregated Revenues	The following table sets forth asset-based revenue at a disaggregated level (dollars in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Asset-based revenue Money market cash sweep fees $ 5,762 $ 4,199 $ 15,576 $ 15,645 Other cash sweep vehicles fees (1) 121,412 77,418 337,068 197,470 Total cash sweep revenue 127,174 81,617 352,644 213,115 Sponsorship programs 58,065 48,292 168,074 143,458 Recordkeeping 63,656 54,044 186,116 158,053 Total asset-based revenue $ 248,895 $ 183,953 $ 706,834 $ 514,626 (1) Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Transaction and Fee Revenue Point-in-time (1) $ 78,465 $ 66,244 $ 240,954 $ 213,182 Over time (2) 40,476 37,755 111,091 108,340 Total transaction and fee revenue 118,941 103,999 352,045 321,522 Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Sales-based Variable annuities $ 57,491 $ 46,148 $ 168,487 $ 150,103 Mutual funds 33,319 30,638 107,910 102,009 Alternative investments 1,822 2,550 5,457 11,348 Fixed annuities 40,040 27,906 107,709 94,930 Equities 19,082 17,748 62,071 58,520 Fixed income 25,757 17,967 74,587 60,371 Insurance 14,433 15,906 46,877 46,914 Group annuities 1,273 1,098 3,615 3,929 Other 328 137 595 392 Total sales-based revenue $ 193,545 $ 160,098 $ 577,308 $ 528,516 Trailing Variable annuities $ 143,584 $ 117,630 $ 429,126 $ 347,924 Mutual funds 122,260 100,701 362,755 295,314 Alternative investments 4,509 4,126 13,145 9,217 Fixed annuities 7,077 4,858 19,579 14,306 Fixed income 6,387 5,945 18,781 17,293 Insurance 1,722 1,432 5,116 4,441 Group annuities 7,791 8,221 23,961 27,870 Total trailing revenue $ 293,330 $ 242,913 $ 872,463 $ 716,365 Total commission revenue $ 486,875 $ 403,011 $ 1,449,771 $ 1,244,881 Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Variable annuities $ 201,075 $ 163,778 $ 597,613 $ 498,027 Mutual funds 155,579 131,339 470,665 397,323 Alternative investments 6,331 6,676 18,602 20,565 Fixed annuities 47,117 32,764 127,288 109,236 Equities 19,082 17,748 62,071 58,520 Fixed income 32,144 23,912 93,368 77,664 Insurance 16,155 17,338 51,993 51,355 Group annuities 9,064 9,319 27,576 31,799 Other 328 137 595 392 Total commission revenue $ 486,875 $ 403,011 $ 1,449,771 $ 1,244,881

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Financial assets and financial liabilities measured at fair value on a recurring basis	The following table summarizes the Company’s financial assets and financial liabilities measured at fair value on a recurring basis at September 30, 2018 (in thousands): Level 1 Level 2 Level 3 Total Assets Cash equivalents $ 85,721 $ — $ — $ 85,721 Securities owned — trading: Money market funds 169 — — 169 Mutual funds 9,966 — — 9,966 Equity securities 2,726 — — 2,726 Debt securities — 1 — 1 U.S. treasury obligations 19,593 — — 19,593 Total securities owned — trading 32,454 1 — 32,455 Other assets 204,004 8,606 — 212,610 Total assets at fair value $ 322,179 $ 8,607 $ — $ 330,786 Liabilities Equity securities $ 175 $ — $ — $ 175 Debt securities — 158 — 158 Total securities sold, but not yet purchased 175 158 — 333 Total liabilities at fair value $ 175 $ 158 $ — $ 333 The following table summarizes the Company’s financial assets and financial liabilities measured at fair value on a recurring basis at December 31, 2017 (in thousands): Level 1 Level 2 Level 3 Total Assets Cash equivalents $ 147,034 $ — $ — $ 147,034 Securities owned — trading: Money market funds 288 — — 288 Mutual funds 10,850 — — 10,850 Equity securities 201 — — 201 Debt securities — 60 — 60 U.S. treasury obligations 6,480 — — 6,480 Total securities owned — trading 17,819 60 — 17,879 Other assets 180,377 9,282 — 189,659 Total assets at fair value $ 345,230 $ 9,342 $ — $ 354,572 Liabilities Securities sold, but not yet purchased: Mutual funds $ 3 $ — $ — $ 3 Equity securities 67 — — 67 Debt securities — 1,112 — 1,112 Total securities sold, but not yet purchased 70 1,112 — 1,182 Total liabilities at fair value $ 70 $ 1,112 $ — $ 1,182

Held-to-Maturity Securities (Ta

Held-to-Maturity Securities (Tables)	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Summary of amortized cost, gross unrealized gain (loss), and fair value of securities held-to-maturity	The amortized cost, gross unrealized loss, and fair value of securities held-to-maturity were as follows (in thousands): September 30, December 31, Amortized cost $ 13,005 $ 11,833 Gross unrealized loss (123 ) (86 ) Fair value $ 12,882 $ 11,747
Maturities of securities held-to-maturity	At September 30, 2018 , the securities held-to-maturity were scheduled to mature as follows (in thousands): Within one year After one but within five years After five but within ten years Total U.S. government notes — at amortized cost $ 4,995 $ 8,010 $ — $ 13,005 U.S. government notes — at fair value $ 4,961 $ 7,921 $ — $ 12,882

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets Schedule of goodwill (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill [Line Items]
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	Future amortization expense is estimated as follows (in thousands): 2018 - remainder $ 15,673 2019 62,688 2020 62,297 2021 62,140 2022 61,340 Thereafter 178,277 Total $ 442,415
Schedule of Goodwill [Table Text Block]	A summary of the activity in goodwill is presented below (in thousands): Balance at December 31, 2016 $ 1,365,838 Goodwill acquired 61,931 Balance at December 31, 2017 $ 1,427,769 Goodwill acquired 49,006 Balance at September 30, 2018 $ 1,476,775
Schedule of Intangible Assets and Goodwill [Table Text Block]	The components of intangible assets were as follows at September 30, 2018 (dollars in thousands): Weighted-Average Life Remaining (in years) Gross Carrying Value Accumulated Amortization Net Carrying Value Definite-lived intangible assets: Advisor and financial institution relationships 7.3 $ 651,642 $ (303,823 ) $ 347,819 Product sponsor relationships 7.4 234,086 (146,547 ) 87,539 Client relationships 6.2 19,133 (12,506 ) 6,627 Trade names 3.6 1,200 (770 ) 430 Total definite-lived intangible assets $ 906,061 $ (463,646 ) $ 442,415 Indefinite-lived intangible assets: Trademark and trade name 39,819 Total intangible assets $ 482,234 The components of intangible assets were as follows at December 31, 2017 (dollars in thousands): Weighted-Average Life Remaining (in years) Gross Carrying Value Accumulated Amortization Net Carrying Value Definite-lived intangible assets: Advisor and financial institution relationships 8.0 $ 538,921 $ (269,294 ) $ 269,627 Product sponsor relationships 8.1 234,086 (137,615 ) 96,471 Client relationships 6.8 19,133 (11,477 ) 7,656 Trade names 4.3 1,200 (680 ) 520 Total definite-lived intangible assets $ 793,340 $ (419,066 ) $ 374,274 Indefinite-lived intangible assets: Trademark and trade name 39,819 Total intangible assets $ 414,093

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Outstanding borrowings	The Company’s outstanding long-term borrowings as of the dates below were as follows (dollars in thousands): September 30, 2018 December 31, 2017 Long-Term Borrowings Balance Applicable Margin Interest Rate Balance Applicable Margin Interest rate Maturity Revolving Credit Facility $ — LIBOR+125bps — % $ — LIBOR+125bps — % 9/21/2022 Senior Secured Term Loan B (1) 1,485,000 LIBOR+225 bps 4.42 % 1,496,250 LIBOR+225 bps 3.81 % 9/21/2024 Senior Unsecured Notes (1)(2) 900,000 Fixed Rate 5.75 % 900,000 Fixed Rate 5.75 % 9/15/2025 Total long-term borrowings 2,385,000 2,396,250 Plus: Unamortized Premium 10,458 11,584 Less: Unamortized Debt Issuance Cost (20,345 ) (22,812 ) Net Carrying Value $ 2,375,113 $ 2,385,022

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2018
Equity, Class of Treasury Stock [Line Items]
Summary of share repurchase program activity	The Company had the following activity under its approved share repurchase program (in millions, except share and per share data): 2018 Total Number of Shares Purchased Weighted-Average Price Paid Per Share Total Cost (1) First quarter 967,500 $ 62.84 $ 60.8 Second quarter 1,791,493 $ 65.20 $ 116.8 Third quarter 1,849,027 $ 66.24 $ 122.5 4,608,020 $ 65.12 $ 300.1
Dividends Declared [Table Text Block]	Cash dividends per share of common stock and total cash dividends paid on a quarterly basis were as follows (in millions, except per share data): 2018 2017 Dividend per Share Total Cash Dividend Dividend per Share Total Cash Dividend First quarter $ 0.25 $ 22.6 $ 0.25 $ 22.6 Second quarter $ 0.25 $ 22.3 $ 0.25 $ 22.6 Third quarter $ 0.25 $ 21.9 $ 0.25 $ 22.5

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted-average assumptions used for calculating the fair value of stock options and warrants with the Black-Scholes valuation model	The following table presents the weighted-average assumptions used in the Black-Scholes valuation model by the Company in calculating the fair value of its employee and officer stock options granted during the nine months ended September 30, 2018 : Expected life (in years) 5.43 Expected stock price volatility 34.80 % Expected dividend yield 1.71 % Risk-free interest rate 2.66 % Fair value of options $ 19.86
Summary of stock option and warrant activity	The following table summarizes the Company’s stock option and warrant activity for the nine months ended September 30, 2018 : Number of Shares Weighted- Average Exercise Price Weighted-Average Remaining Contractual Term (Years) Aggregate Intrinsic Value (In thousands) Outstanding — December 31, 2017 4,866,499 $ 31.73 Granted 478,824 $ 65.55 Exercised (1,218,087 ) $ 33.95 Forfeited and Expired (208,091 ) $ 37.81 Outstanding — September 30, 2018 3,919,145 $ 34.85 5.79 $ 116,683 Exercisable — September 30, 2018 2,682,517 $ 31.07 4.54 $ 89,711 Exercisable and expected to vest — September 30, 2018 3,857,324 $ 34.50 5.73 $ 116,157
Summary of outstanding stock options and warrant information	The following table summarizes information about outstanding stock options and warrants as of September 30, 2018 : Outstanding Exercisable Range of Exercise Prices Number of Shares Weighted- Average Exercise Price Weighted-Average Number of Shares Weighted- Average Exercise Price $18.01 - $25.00 1,305,007 $ 20.54 5.32 947,556 $ 20.72 $25.01 - $30.00 397,714 $ 28.95 3.75 395,640 $ 28.94 $30.01 - $35.00 706,538 $ 33.13 3.07 706,538 $ 33.13 $35.01 - $45.00 665,708 $ 39.62 8.24 224,812 $ 39.77 $45.01 - $55.00 405,955 $ 48.72 6.08 405,955 $ 48.72 $55.01 - $71.00 438,223 $ 65.55 9.41 2,016 $ 65.50 3,919,145 $ 34.85 5.79 2,682,517 $ 31.07
Summary of restricted stock awards and restricted stock units activity	The following summarizes the Company’s activity in its restricted stock awards and stock units, which include restricted stock units, deferred stock units, and performance stock units, for the nine months ended September 30, 2018 : Restricted Stock Awards Stock Units Number of Shares Weighted-Average Grant-Date Fair Value Number of Shares Weighted-Average Grant-Date Fair Value Nonvested — December 31, 2017 12,796 $ 39.73 957,123 $ 32.81 Granted 7,057 $ 70.26 333,061 $ 69.60 Vested (12,796 ) $ 39.73 (361,535 ) $ 34.41 Forfeited — $ — (69,881 ) $ 39.04 Nonvested — September 30, 2018 7,057 $ 70.26 858,768 $ 45.89 Expected to vest — September 30, 2018 7,057 $ 70.26 800,959 $ 44.78

Earnings per Share (Tables)

Earnings per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Basic and diluted earnings per share computations	The calculation of basic and diluted earnings per share is as follows (in thousands, except per share data): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Net income $ 106,865 $ 58,142 $ 319,161 $ 174,765 Basic weighted-average number of shares outstanding 87,426 89,967 88,841 90,029 Dilutive common share equivalents 2,452 2,075 2,606 1,998 Diluted weighted-average number of shares outstanding 89,878 92,042 91,447 92,027 Basic earnings per share $ 1.22 $ 0.65 $ 3.59 $ 1.94 Diluted earnings per share $ 1.19 $ 0.63 $ 3.49 $ 1.90

Organization and Description _2

Organization and Description of the Company Consolidation, Parent Ownership Interest (Details)	9 Months Ended
	Sep. 30, 2018
Lpl Financial Llc [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Ownership Interest Percentage In Subsidiary	100.00%
Number of States in which Entity Operates	50
Ptc Holdings Inc [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Ownership Interest Percentage In Subsidiary	100.00%

Summary of Significant Accoun_3

Summary of Significant Accounting Policies Reportable Segment (Details)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Number of Reportable Segments	1

Summary of Significant Accoun_4

Summary of Significant Accounting Policies Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total borrowings	$ 2,385,000	$ 2,396,250
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of indebtedness	$ 2,371,700	$ 2,422,000

Revenue Disaggregation of Reven

Revenue Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Commission revenue	$ 486,875	$ 403,011	$ 1,449,771	$ 1,244,881
Other cash sweep vehicles fee revenue	7,687	10,038	14,891	32,760
Unearned revenue recognized			71,300
Recognized at a Point-in-time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	193,545	160,098	577,308	528,516
Recognized over time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	293,330	242,913	872,463	716,365
Asset-based Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	248,895	183,953	706,834	514,626
Cash-sweep Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	127,174	81,617	352,644	213,115
Money Market Cash Sweep Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5,762	4,199	15,576	15,645
Other Cash Sweep Vehicle Revenues [Member]
Disaggregation of Revenue [Line Items]
Other cash sweep vehicles fee revenue	121,412	77,418	337,068	197,470
Sponsorship Programs [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	58,065	48,292	168,074	143,458
Recordkeeping Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	63,656	54,044	186,116	158,053
Transaction and Fee Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	118,941	103,999	352,045	321,522
Transaction and Fee Revenue [Member] | Recognized at a Point-in-time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	78,465	66,244	240,954	213,182
Transaction and Fee Revenue [Member] | Recognized over time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	40,476	37,755	111,091	108,340
Variable Annuities [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	201,075	163,778	597,613	498,027
Variable Annuities [Member] | Recognized at a Point-in-time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	57,491	46,148	168,487	150,103
Variable Annuities [Member] | Recognized over time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	143,584	117,630	429,126	347,924
Mutual Funds [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	155,579	131,339	470,665	397,323
Mutual Funds [Member] | Recognized at a Point-in-time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	33,319	30,638	107,910	102,009
Mutual Funds [Member] | Recognized over time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	122,260	100,701	362,755	295,314
Alternative Investments [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	6,331	6,676	18,602	20,565
Alternative Investments [Member] | Recognized at a Point-in-time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	1,822	2,550	5,457	11,348
Alternative Investments [Member] | Recognized over time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	4,509	4,126	13,145	9,217
Fixed Annuities [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	47,117	32,764	127,288	109,236
Fixed Annuities [Member] | Recognized at a Point-in-time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	40,040	27,906	107,709	94,930
Fixed Annuities [Member] | Recognized over time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	7,077	4,858	19,579	14,306
Equities [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	19,082	17,748	62,071	58,520
Equities [Member] | Recognized at a Point-in-time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	19,082	17,748	62,071	58,520
Fixed Income [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	32,144	23,912	93,368	77,664
Fixed Income [Member] | Recognized at a Point-in-time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	25,757	17,967	74,587	60,371
Fixed Income [Member] | Recognized over time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	6,387	5,945	18,781	17,293
Insurance [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	16,155	17,338	51,993	51,355
Insurance [Member] | Recognized at a Point-in-time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	14,433	15,906	46,877	46,914
Insurance [Member] | Recognized over time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	1,722	1,432	5,116	4,441
Group Annuity [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	9,064	9,319	27,576	31,799
Group Annuity [Member] | Recognized at a Point-in-time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	1,273	1,098	3,615	3,929
Group Annuity [Member] | Recognized over time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	7,791	8,221	23,961	27,870
Other [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	328	137	595	392
Other [Member] | Recognized at a Point-in-time [Member]
Disaggregation of Revenue [Line Items]
Commission revenue	$ 328	$ 137	$ 595	$ 392

Acquisitions (Details)

Acquisitions (Details) - USD ($) $ in Thousands	Aug. 15, 2017	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired		$ 112,700			$ 98,400
Goodwill, Acquired During Period		$ 49,000	$ 49,006		$ 61,931
Payments to Acquire Businesses, Gross	$ 325,000		$ 0	$ 325,000

Fair Value Measurements Financi

Fair Value Measurements Financial Assets and Liabilities Measured on a Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	$ 32,455	$ 17,879
Securities sold, but not yet purchased	333	1,182
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	85,721	147,034
Securities owned — trading	32,455	17,879
Other assets	212,610	189,659
Assets, Fair Value Disclosure	330,786	354,572
Securities sold, but not yet purchased	333	1,182
Total liabilities at fair value	333	1,182
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	85,721	147,034
Securities owned — trading	32,454	17,819
Other assets	204,004	180,377
Assets, Fair Value Disclosure	322,179	345,230
Securities sold, but not yet purchased	175	70
Total liabilities at fair value	175	70
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Securities owned — trading	1	60
Other assets	8,606	9,282
Assets, Fair Value Disclosure	8,607	9,342
Securities sold, but not yet purchased	158	1,112
Total liabilities at fair value	158	1,112
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Securities owned — trading	0	0
Other assets	0	0
Assets, Fair Value Disclosure	0	0
Securities sold, but not yet purchased	0	0
Total liabilities at fair value	0	0
Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, but not yet purchased		3
Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, but not yet purchased		3
Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, but not yet purchased		0
Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, but not yet purchased		0
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, but not yet purchased	175	67
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, but not yet purchased	175	67
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, but not yet purchased	0	0
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, but not yet purchased	0	0
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, but not yet purchased	158	1,112
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, but not yet purchased	0	0
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, but not yet purchased	158	1,112
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, but not yet purchased	0	0
Money Market Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	169	288
Money Market Funds [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	169	288
Money Market Funds [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	0	0
Money Market Funds [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	0	0
Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	9,966	10,850
Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	9,966	10,850
Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	0	0
Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	0	0
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	2,726	201
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	2,726	201
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	0	0
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	0	0
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	1	60
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	0	0
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	1	60
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	0	0
U.S. treasury obligations | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	19,593	6,480
U.S. treasury obligations | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	19,593	6,480
U.S. treasury obligations | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	0	0
U.S. treasury obligations | Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities owned — trading	$ 0	$ 0

Held-to-Maturity Securities (De

Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Summary of amortized cost, gross unrealized (loss) gain and fair value of securities held-to-maturity
U.S. government notes - at amortized cost, Total	$ 13,005	$ 11,833
U.S. government notes
Summary of amortized cost, gross unrealized (loss) gain and fair value of securities held-to-maturity
U.S. government notes - at amortized cost, Total	13,005	11,833
Gross unrealized loss	(123)	(86)
U.S. government notes - at fair value, Total	$ 12,882	$ 11,747

Held-to-Maturity Securities (_2

Held-to-Maturity Securities (Details 1) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Maturities of securities held-to-maturity
U.S. government notes - at amortized cost, Total	$ 13,005	$ 11,833
U.S. government notes
Maturities of securities held-to-maturity
U.S. government notes - at amortized cost, Within one year	4,995
U.S. government notes - at amortized cost, After one but within five years	8,010
U.S. government notes - at amortized cost, After five through ten years	0
U.S. government notes - at amortized cost, Total	13,005	11,833
U.S. government notes - at fair value, Within one year	4,961
U.S. government notes - at fair value, After one but within five years	7,921
U.S. government notes - at fair value, After five through ten years	0
U.S. government notes - at fair value, Total	$ 12,882	$ 11,747

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Goodwill		$ 1,476,775	$ 1,427,769	$ 1,365,838
Goodwill, Acquired During Period	$ 49,000	$ 49,006	$ 61,931

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets Intangible assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 15,676	$ 9,352	$ 44,580	$ 28,296
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	15,673		15,673
Finite-Lived Intangible Assets, Gross	906,061		906,061		$ 793,340
Accumulated amortization, Intangible assets	463,646		463,646		419,066
Finite-Lived Intangible Assets, Net	442,415		442,415		374,274
Intangible Assets, Net (Excluding Goodwill)	482,234		482,234		$ 414,093
Finite-Lived Intangible Assets, Amortization Expense, Year Two	62,688		62,688
Finite-Lived Intangible Assets, Amortization Expense, Year Three	62,297		62,297
Finite-Lived Intangible Assets, Amortization Expense, Year Four	62,140		62,140
Finite-Lived Intangible Assets, Amortization Expense, Year Five	61,340		61,340
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	178,277		$ 178,277
Advisor And Financial Institution Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			7 years 3 months 18 days		8 years
Finite-Lived Intangible Assets, Gross	651,642		$ 651,642		$ 538,921
Accumulated amortization, Intangible assets	303,823		303,823		269,294
Finite-Lived Intangible Assets, Net	347,819		$ 347,819		$ 269,627
Product Sponsor Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			7 years 4 months 24 days		8 years 1 month 6 days
Finite-Lived Intangible Assets, Gross	234,086		$ 234,086		$ 234,086
Accumulated amortization, Intangible assets	146,547		146,547		137,615
Finite-Lived Intangible Assets, Net	87,539		$ 87,539		$ 96,471
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			6 years 2 months 12 days		6 years 9 months 18 days
Finite-Lived Intangible Assets, Gross	19,133		$ 19,133		$ 19,133
Accumulated amortization, Intangible assets	12,506		12,506		11,477
Finite-Lived Intangible Assets, Net	6,627		$ 6,627		$ 7,656
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			3 years 7 months 6 days		4 years 3 months 18 days
Finite-Lived Intangible Assets, Gross	1,200		$ 1,200		$ 1,200
Accumulated amortization, Intangible assets	770		770		680
Finite-Lived Intangible Assets, Net	430		430		520
Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets (Excluding Goodwill)	$ 39,819		$ 39,819		$ 39,819

Debt (Credit Agreement Textuals

Debt (Credit Agreement Textuals) (Details) - USD ($) $ in Thousands	Sep. 21, 2017	Mar. 10, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Principal amount of debt			$ 2,375,113		$ 2,375,113		$ 2,385,022
Long-term Debt, Gross			2,385,000		2,385,000		2,396,250
Loss on extinguishment of debt			0	$ 1,268	0	$ 22,407
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt term	5 years
Line of credit, maximum borrowing capacity	$ 500,000
Long-term Debt, Gross			0		$ 0		0
Applicable interest rate margin (as percent)					1.25%
Letters of credit, amount outstanding			10,600		$ 10,600
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Applicable interest rate margin (as percent)	1.25%
Secured Debt [Member] | Fourth Amendment Agreement Term Loan B [Member]
Debt Instrument [Line Items]
Debt term	7 years
Long-term Debt, Gross	$ 1,695,800		1,485,000		1,485,000		1,496,250
Amortization payment (as percent)		0.25%
Secured Debt [Member] | Fourth Amendment Agreement Term Loan B [Member] | Eurodollar Rate [Member]
Debt Instrument [Line Items]
Applicable interest rate margin (as percent)	2.25%
Interest Rate Floor	0.00%
Secured Debt [Member] | Fourth Amendment Agreement Term Loan B [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Applicable interest rate margin (as percent)	2.25%
Secured Debt [Member] | Fourth Amendment Agreement Term Loan B [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable interest rate margin (as percent)	1.25%
Unsecured Debt [Member] | Additional Senior Unsecured Notes due 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 400,000
Debt Instrument, Redemption Price, Percentage	103.00%
Unsecured Debt [Member] | Senior Notes Due 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 500,000	$ 900,000		$ 900,000		$ 900,000
Interest Rate (as percent)			5.75%		5.75%		5.75%
Redemption price (as percent)			100.00%
Line of Credit [Member] | Revolving Credit Facility [Member] | Eurodollar Rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Applicable interest rate margin (as percent)	1.25%
Line of Credit [Member] | Revolving Credit Facility [Member] | Eurodollar Rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Applicable interest rate margin (as percent)	1.75%
Line of Credit [Member] | Revolving Credit Facility [Member] | Base Rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Applicable interest rate margin (as percent)	0.25%
Line of Credit [Member] | Revolving Credit Facility [Member] | Base Rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Applicable interest rate margin (as percent)	0.75%

Debt (Credit Agreement Outstand

Debt (Credit Agreement Outstanding) (Details) - USD ($) $ in Thousands	Sep. 21, 2017	Sep. 30, 2018	Dec. 31, 2017	Mar. 10, 2017
Debt Instrument [Line Items]
Total borrowings		$ 2,385,000	$ 2,396,250
Less Unamortized Debt Issuance Cost		(20,345)	(22,812)
Debt Instrument, Unamortized Premium		10,458	11,584
Long-term borrowings — net of unamortized debt issuance cost		2,375,113	2,385,022
Secured Debt [Member] | Fourth Amendment Agreement Term Loan B [Member]
Debt Instrument [Line Items]
Total borrowings	$ 1,695,800	$ 1,485,000	$ 1,496,250
Interest Rate (as percent)		4.42%	3.81%
Secured Debt [Member] | Fourth Amendment Agreement Term Loan B [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Applicable margin (as percent)	2.25%
Unsecured Debt [Member] | Senior Notes Due 2025 [Member]
Debt Instrument [Line Items]
Total borrowings		$ 900,000	$ 900,000	$ 500,000
Interest Rate (as percent)		5.75%	5.75%
Unsecured Debt [Member] | Additional Senior Unsecured Notes due 2025 [Member]
Debt Instrument [Line Items]
Total borrowings	$ 400,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Total borrowings		$ 0	$ 0
Applicable margin (as percent)		1.25%
Interest Rate (as percent)		0.00%	0.00%
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Applicable margin (as percent)	1.25%

Debt Debt (Bank Loans Payable T

Debt Debt (Bank Loans Payable Textuals) (Details)	Sep. 21, 2017USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2017USD ($)
Line of Credit Facility [Line Items]
Long-term Debt, Gross		$ 2,385,000,000	$ 2,396,250,000
Outstanding amount		$ 160,000,000
Interest rate (as percent)		2.99%
Line of Credit [Member]
Line of Credit Facility [Line Items]
Total number of uncommitted lines of credit		3
Number of uncommitted lines of credit with an unspecified limit		2
Line of credit, maximum borrowing capacity		$ 200,000,000
Line of credit, amount outstanding		$ 0
Additional Senior Unsecured Notes due 2025 [Member] | Unsecured Debt [Member]
Line of Credit Facility [Line Items]
Long-term Debt, Gross	$ 400,000,000
Debt Instrument, Redemption Price, Percentage	103.00%

Commitments and Contingencies (

Commitments and Contingencies (Leases) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Leases, Operating [Abstract]
Rent expense, operating leases	$ 4.8	$ 4.8	$ 14.3	$ 15.3

Commitments and Contingencies C

Commitments and Contingencies Commitments and Contingencies (Other Commitments) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Brokers and Dealers [Abstract]
Collateral Securities Repledged, Delivered, or Used	$ 293,500
Collateral security	410,900
Amount pledged with client-owned securities	56,500
Remaining collateral securities that can be re-pledged, loaned, or sold	354,300
Security Owned and Pledged as Collateral, Fair Value [Abstract]
Trading securities pledged to clearing organizations	4,700	$ 6,500
Leasehold Financing Obligation	$ 105,057	$ 107,518

Commitments and Contingencies_2

Commitments and Contingencies Commitments and Contingencies (Legal) (Details)	Sep. 30, 2018USD ($)
Loss Contingencies [Line Items]
Loss Contingency Accrual	$ 26,400,000

Stockholders' Equity (Dividends

Stockholders' Equity (Dividends Paid) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Stockholders' Equity Note [Abstract]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25
Dividends	$ 21,900	$ 22,300	$ 22,600	$ 22,500	$ 22,600	$ 22,600
Total cash dividends paid during the quarter							$ 66,847	$ 67,765

Stockholdes' Equity (Share Repu

Stockholdes' Equity (Share Repurchases) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017
Equity, Class of Treasury Stock [Line Items]
Amount Remaining	$ 200,000			$ 200,000
Shares Purchased	1,849,027	1,791,493	967,500	4,608,020
Weighted-Average Price Paid Per Share	$ 66.24	$ 65.20	$ 62.84	$ 65.12
Total Cost	$ 122,500	$ 116,800	$ 60,800	$ 300,091	$ 83,721
Commission Fee Paid Per Repurchased Share				$ 0.02

Share-Based Compensation (Texua

Share-Based Compensation (Texuals) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares	20,055,945		20,055,945
Authorized unissued shares	6,630,320		6,630,320
Share-based compensation:
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	6,484,606		6,484,606
Employees, officers, and directors [Member] | Stock options and warrants [Member]
Share-based compensation:
Share-based compensation	$ 2.5	$ 2	$ 6.5	$ 5.8
Share-based compensation cost unrecognized	9.4		$ 9.4
Non-vested compensation cost weighted-average period			1 year 11 months 23 days
Employees, officers, and directors [Member] | Restricted Stock [Member]
Share-based compensation:
Share-based compensation	3.6	2.7	$ 10.6	8.9
Share-based compensation cost unrecognized	19.6		$ 19.6
Non-vested compensation cost weighted-average period			2 years 1 month 20 days
Advisors and Financial Institutions [Member] | Restricted stock units (RSUs) [Member]
Share-based compensation:
Share-based compensation	1	$ 2.3	$ 5.5	$ 5.3
Share-based compensation cost unrecognized	$ 5.8		$ 5.8
Non-vested compensation cost weighted-average period			1 year 9 months 14 days

Share-Based Compensation Stock

Share-Based Compensation Stock Option and Warrant Assumptions (Details) - Stock options and warrants [Member] - Employees, officers, and directors [Member]	9 Months Ended
	Sep. 30, 2018$ / shares
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected life (in years)	5 years 5 months 4 days
Expected stock price volatility	34.80%
Expected dividend yield	1.71%
Risk-free interest rate	2.66%
Fair value of options	$ 19.86

Share-Based Compensation Stoc_2

Share-Based Compensation Stock Option and Warrant Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Shares Outstanding, Beginning Balance	4,866,499
Number of Shares, Granted	478,824
Number of Shares, Exercised	(1,218,087)
Number of Shares, Forfeited	(208,091)
Number of Shares Outstanding, Ending Balance	3,919,145
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number	3,857,324
Number of Shares Exercisable, Ending Balance	2,682,517
Weighted-Average Exercise Price, Granted	$ 65.55
Weighted-Average Exercise Price, Exercised	33.95
Weighted-Average Exercise Price, Forfeited	37.81
Weighted-Average Exercise Price, Outstanding, Ending Balance	34.85	$ 31.73
Weighted-Average Exercise Price, Exercisable, Ending Balance	$ 31.07
Weighted-Average Remaining Contractual Term, Options Outstanding	5 years 9 months 14 days
Weighted-Average Remaining Contractual Term, Options Exercisable	4 years 6 months 14 days
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 116,683
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 89,711
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price	$ 34.50
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Remaining Contractual Term	5 years 8 months 23 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value	$ 116,157

Share-Based Compensation Outsta

Share-Based Compensation Outstanding Stock Options and Warrant Information (Details)	9 Months Ended
	Sep. 30, 2018$ / sharesshares
Summary information about outstanding stock options and warrants
Total number of shares, Outstanding | shares	3,919,145
Weighted-average remaining life (years), Outstanding	5 years 9 months 14 days
Weighted-average exercise price, Outstanding | $ / shares	$ 34.85
Number of shares, Exercisable | shares	2,682,517
Weighted-average exercise price, Exercisable | $ / shares	$ 31.07
$18.01 - $25.00
Summary information about outstanding stock options and warrants
Total number of shares, Outstanding | shares	1,305,007
Weighted-average remaining life (years), Outstanding	5 years 3 months 25 days
Weighted-average exercise price, Outstanding | $ / shares	$ 20.54
Number of shares, Exercisable | shares	947,556
Weighted-average exercise price, Exercisable | $ / shares	$ 20.72
$25.01 - $30.00
Summary information about outstanding stock options and warrants
Total number of shares, Outstanding | shares	397,714
Weighted-average remaining life (years), Outstanding	3 years 9 months
Weighted-average exercise price, Outstanding | $ / shares	$ 28.95
Number of shares, Exercisable | shares	395,640
Weighted-average exercise price, Exercisable | $ / shares	$ 28.94
$30.01 - $35.00
Summary information about outstanding stock options and warrants
Total number of shares, Outstanding | shares	706,538
Weighted-average remaining life (years), Outstanding	3 years 25 days
Weighted-average exercise price, Outstanding | $ / shares	$ 33.13
Number of shares, Exercisable | shares	706,538
Weighted-average exercise price, Exercisable | $ / shares	$ 33.13
$35.01 - $45.00
Summary information about outstanding stock options and warrants
Total number of shares, Outstanding | shares	665,708
Weighted-average remaining life (years), Outstanding	8 years 2 months 26 days
Weighted-average exercise price, Outstanding | $ / shares	$ 39.62
Number of shares, Exercisable | shares	224,812
Weighted-average exercise price, Exercisable | $ / shares	$ 39.77
$45.01 - $55.00
Summary information about outstanding stock options and warrants
Total number of shares, Outstanding | shares	405,955
Weighted-average remaining life (years), Outstanding	6 years 29 days
Weighted-average exercise price, Outstanding | $ / shares	$ 48.72
Number of shares, Exercisable | shares	405,955
Weighted-average exercise price, Exercisable | $ / shares	$ 48.72
$55.01 - $71.00
Summary information about outstanding stock options and warrants
Total number of shares, Outstanding | shares	438,223
Weighted-average remaining life (years), Outstanding	9 years 4 months 28 days
Weighted-average exercise price, Outstanding | $ / shares	$ 65.55
Number of shares, Exercisable | shares	2,016
Weighted-average exercise price, Exercisable | $ / shares	$ 65.50

Restricted Stock Activity (Deta

Restricted Stock Activity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price					$ 70.26
Restricted stock awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of Shares, Beginning Balance			12,796
Number of Shares, Granted			7,057
Number of Shares, Vested			(12,796)
Number of Shares, Forfeited			0
Number of Shares, Ending Balance	7,057		7,057
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number					7,057
Weighted-Average Grant-Date Fair Value, Beginning Balance	$ 70.26		$ 70.26		$ 70.26	$ 39.73
Weighted-Average Grant-Date Fair Value, Granted			70.26
Weighted-Average Grant-Date Fair Value, Vested			39.73
Weighted-Average Grant-Date Fair Value, Forfeited			0
Weighted-Average Grant-Date Fair Value, Ending Balance	$ 70.26		$ 70.26
Restricted stock units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of Shares, Beginning Balance			957,123
Number of Shares, Granted			333,061
Number of Shares, Vested			(361,535)
Number of Shares, Forfeited			(69,881)
Number of Shares, Ending Balance	858,768		858,768
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number					800,959
Weighted-Average Grant-Date Fair Value, Beginning Balance	$ 45.89		$ 45.89		$ 45.89	$ 32.81
Weighted-Average Grant-Date Fair Value, Granted			69.60
Weighted-Average Grant-Date Fair Value, Vested			34.41
Weighted-Average Grant-Date Fair Value, Forfeited			39.04
Weighted-Average Grant-Date Fair Value, Ending Balance	$ 45.89		$ 45.89
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price					$ 44.78
Advisors and Financial Institutions [Member] | Restricted stock units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 1	$ 2.3	$ 5.5	$ 5.3
Employees, officers, and directors [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	3.6	2.7	10.6	8.9
Employees, officers, and directors [Member] | Stock options and warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 2.5	$ 2	$ 6.5	$ 5.8

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, $ 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	$ 106,865	$ 58,142	$ 319,161	$ 174,765
Basic weighted-average number of shares outstanding	87,426,000	89,967,000	88,841,000	90,029,000
Dilutive common share equivalents	2,452,000	2,075,000	2,606,000	1,998,000
Diluted weighted-average number of shares outstanding	89,878,000	92,042,000	91,447,000	92,027,000
Basic earnings per share	$ 1.22	$ 0.65	$ 3.59	$ 1.94
Diluted earnings per share	$ 1.19	$ 0.63	$ 3.49	$ 1.90
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	439,156	1,168,772	377,583	2,098,029

Earnings per Share (Textuals) (

Earnings per Share (Textuals) (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of Earnings per Share amount	439,156	1,168,772	377,583	2,098,029

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal statutory income tax rate			21.00%		35.00%
Effective income tax rate	27.50%	39.80%	25.80%	38.60%

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Related Party Transaction [Line Items]
Shareholder Percent Ownership in Company			10.00%
Revenue from related party transactions	$ 1	$ 0.7	$ 2.6	$ 2.2
Related party transactions expenses	$ 0.6	$ 0	$ 1.8	$ 0.1

Net Capital and Regulatory Re_2

Net Capital and Regulatory Requirements (Details) $ in Millions	Sep. 30, 2018USD ($)
Net capital and net capital requirements for the Company's broker-dealer subsidiaries
Net Capital	$ 166.1
Minimum Net Capital Required for Broker-Dealer Subsidiary	$ 8.5

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events (Details) - Subsequent Event [Member] - $ / shares	Nov. 26, 2018	Nov. 08, 2018	Oct. 23, 2018
Subsequent Event [Line Items]
Dividends Payable, Date Declared			Oct. 23, 2018
Dividends Payable, Amount Per Share			$ 0.25
Dividends Payable, Date to be Paid	Nov. 26, 2018
Dividends Payable, Date of Record		Nov. 8, 2018