Texas Capital Bancshares (TCBI) 10-K 14 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 13, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	TEXAS CAPITAL BANCSHARES INC/TX
Entity Central Index Key	1,077,428
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		49,650,549
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 4,471,032,000

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and due from banks	$ 178,010	$ 113,707
Interest-bearing deposits	2,697,581	2,700,645
Federal funds sold and securities purchased under resale agreements	30,000	25,000
Securities, available-for-sale	23,511	24,874
Loans held for sale ($1,007.7 million and $968.9 million at December 2017 and 2016, respectively, at fair value)	1,011,004	968,929
Loans held for investment, mortgage finance	5,308,160	4,497,338
Loans held for investment (net of unearned income)	15,366,252	13,001,011
Less: Allowance for loan losses	(184,655)	(168,126)
Loans held for investment, net	20,489,757	17,330,223
Mortgage servicing rights, net	85,327	28,536
Premises and equipment, net	25,176	19,775
Accrued interest receivable and other assets	516,239	465,933
Goodwill and intangible assets, net	19,040	19,512
Total assets	25,075,645	21,697,134
Deposits:
Non-interest-bearing	7,812,660	7,994,201
Interest-bearing	11,310,520	9,022,630
Total deposits	19,123,180	17,016,831
Accrued interest payable	7,680	5,498
Other liabilities	182,212	161,223
Federal funds purchased and repurchase agreements	365,040	109,575
Other borrowings	2,800,000	2,000,000
Subordinated notes, net	281,406	281,044
Trust preferred subordinated debentures	113,406	113,406
Total liabilities	22,872,924	19,687,577
Comprehensive income:
Preferred stock, $.01 par value, $1,000 liquidation value: Authorized shares - 10,000,000; Issued shares - 6,000,000 shares issued at December 31, 2014 and 2013	150,000	150,000
Common stock, $.01 par value: Authorized shares - 100,000,000; Issued shares - 45,735,424 and 41,036,787 at December 31, 2014 and 2013, respectively	496	495
Additional paid-in capital	961,305	955,468
Retained earnings	1,090,500	903,187
Treasury stock (shares at cost: 417 at December 31, 2017 and 2016)	(8)	(8)
Accumulated other comprehensive income, net of taxes	428	415
Total stockholders’ equity	2,202,721	2,009,557
Total liabilities and stockholders’ equity	$ 25,075,645	$ 21,697,134

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Loans held for sale ($1,007.7 million and $968.9 million at December 2017 and 2016, respectively, at fair value)	$ 1,007,695,000	$ 968,929,000
Preferred stock, Liquidation value	$ 1,000	$ 1,000
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	6,000,000	6,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	49,643,761	49,504,079
Treasury stock, shares	417	417

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME AND OTHER COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest income
Interest and fees on loans	$ 846,292	$ 684,582	$ 594,729
Securities	1,066	967	1,254
Federal funds sold and securities purchased under resale agreements	2,542	1,547	682
Deposits in other banks	29,399	16,312	6,293
Total interest income	879,299	703,408	602,958
Interest expense
Deposits	79,886	37,175	24,578
Federal funds purchased	2,592	518	284
Other borrowings	15,137	6,128	2,251
Subordinated notes	16,764	16,764	16,764
Trust preferred subordinated debentures	3,592	3,009	2,551
Total interest expense	117,971	63,594	46,428
Net interest income	761,328	639,814	556,530
Provision for credit losses	44,000	77,000	53,250
Net interest income after provision for credit losses	717,328	562,814	503,280
Non-interest income
Service charges on deposit accounts	12,432	10,341	8,323
Wealth management and trust fee income	6,153	4,268	5,022
Bank owned life insurance (BOLI) income	2,260	2,073	2,011
Brokered loan fees	23,331	25,339	18,661
Servicing income	15,657	1,715	(12)
Swap fees	3,990	2,866	4,275
Other	10,433	14,178	9,458
Total non-interest income	74,256	60,780	47,738
Non-interest expense
Salaries and employee benefits	264,231	228,985	192,610
Net occupancy expense	25,811	23,221	23,182
Marketing	26,787	17,303	16,491
Legal and professional	29,731	23,326	22,150
Communications and technology	31,004	25,562	21,425
FDIC insurance assessment	23,510	24,440	17,231
Servicing related expenses	15,506	1,703	14
Allowance and other carrying costs for OREO	6,437	824	22
Other	42,859	37,033	33,398
Total non-interest expense	465,876	382,397	326,523
Income before income taxes	325,708	241,197	224,495
Income tax expense	128,645	86,078	79,641
Net income	197,063	155,119	144,854
Preferred stock dividends	(9,750)	(9,750)	(9,750)
Net income available to common stockholders	187,313	145,369	135,104
Other comprehensive gain (loss)
Change in unrealized gain on available-for-sale securities arising during period, before tax	19	(467)	(877)
Income tax expense (benefit) related to unrealized loss on available-for-sale securities	6	(164)	(306)
Other comprehensive loss net of tax	13	(303)	(571)
Comprehensive income	$ 197,076	$ 154,816	$ 144,283
Basic earnings per common share
Basic earnings per common share	$ 3.78	$ 3.14	$ 2.95
Diluted earnings per common share
Diluted earnings per common share	$ 3.73	$ 3.11	$ 2.91

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income
Beginning balance - Shares at Dec. 31, 2014		6,000,000	45,735,424			417
Beginning balance - Amount at Dec. 31, 2014	$ 1,484,190	$ 150,000	$ 457	$ 709,738	$ 622,714	$ (8)	$ 1,289
Comprehensive income:
Net income	144,854				144,854
Change in unrealized gain (loss) on available-for-sale securities, net of taxes	(571)						(571)
Comprehensive income	144,283
Tax expense related to exercise of stock-based awards	1,452			1,452
Stock-based compensation expense recognized in earnings	4,597			4,597
Preferred stock dividends	(9,750)				(9,750)
Issuance of stock related to stock-based awards - Shares			138,800
Issuance of stock related to stock-based awards - Amount	(1,239)		$ 2	(1,241)
Ending balance - Amount at Dec. 31, 2015	1,623,533	$ 150,000	$ 459	714,546	757,818	$ (8)	718
Ending balance - Shares at Dec. 31, 2015		6,000,000	45,874,224			417
Comprehensive income:
Net income	155,119				155,119
Change in unrealized gain (loss) on available-for-sale securities, net of taxes	(303)						(303)
Comprehensive income	154,816
Tax expense related to exercise of stock-based awards	1,879			1,879
Stock-based compensation expense recognized in earnings	5,093			5,093
Preferred stock dividends	(9,750)				(9,750)
Issuance of stock related to stock-based awards - Shares			172,459
Issuance of stock related to stock-based awards - Amount	(2,481)		$ 1	(2,482)
Issuance of stock - Shares			3,450,000
Issuance of stock - Amount	236,467		$ 35	236,432
Ending balance - Amount at Dec. 31, 2016	2,009,557	$ 150,000	$ 495	955,468	903,187	$ (8)	415
Ending balance - Shares at Dec. 31, 2016		6,000,000	49,504,079			417
Comprehensive income:
Stock Issued During Period, Shares, Other			7,396
Stock Issued During Period, Value, Other			$ 0	0
Net income	197,063				197,063
Change in unrealized gain (loss) on available-for-sale securities, net of taxes	13						13
Comprehensive income	197,076
Tax expense related to exercise of stock-based awards	0			0
Stock-based compensation expense recognized in earnings	8,079			8,079
Preferred stock dividends	(9,750)				(9,750)
Issuance of stock related to stock-based awards - Shares			106,087
Issuance of stock related to stock-based awards - Amount	(2,241)		$ 1	(2,242)
Issuance of stock - Shares			0
Issuance of stock - Amount	0		$ 0	0
Ending balance - Amount at Dec. 31, 2017	2,202,721	$ 150,000	$ 496	$ 961,305	$ 1,090,500	$ (8)	$ 428
Ending balance - Shares at Dec. 31, 2017		6,000,000	49,643,761			417
Comprehensive income:
Stock Issued During Period, Shares, Other			33,595
Stock Issued During Period, Value, Other	$ 0

CONSOLIDATED STATEMENTS OF STO6

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Income tax expense (benefit) related to unrealized loss on available-for-sale securities	$ 6	$ (164)	$ (306)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net income	$ 197,063	$ 155,119	$ 144,854
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	44,000	77,000	53,250
Deferred tax expense (benefit)	31,276	(2,946)	(3,561)
Depreciation and amortization	27,871	21,814	16,495
Increase in valuation allowance on mortgage servicing rights	2,823	0	0
BOLI income	(2,260)	(2,073)	(2,011)
Stock-based compensation expense	22,019	13,578	12,304
Excess tax benefits from stock-based compensation arrangements	0	(2,013)	(1,499)
Purchases and originations of loans held for sale	(5,556,964)	(3,327,482)	(127,002)
Proceeds from sales and repayments of loans held for sale	5,457,117	2,405,592	40,490
Net (gain) loss on sale of loans held for sale and other assets	2,082	(2,519)	179
Technology write-off	5,285	0	0
OREO write-down	6,111	0	0
Changes in operating assets and liabilities:
Accrued interest receivable and other assets	(114,551)	(59,787)	(61,002)
Accrued interest payable and other liabilities	10,289	(2,576)	(3,554)
Net cash provided by (used in) operating activities	132,161	(726,293)	68,943
Investing activities
Purchases of available-for-sale securities	(97,776)	(1,760)	0
Maturities and calls of available-for-sale securities	94,775	555	2,430
Principal payments received on available-for-sale securities	4,383	5,856	8,419
Originations of mortgage finance loans	(86,931,566)	(100,574,326)	(86,342,672)
Proceeds from pay-offs of mortgage finance loans	86,120,744	101,043,264	85,478,521
Net increase in loans held for investment, excluding mortgage finance loans	(2,395,063)	(1,321,733)	(1,603,880)
Purchase of premises and equipment, net	(12,265)	(2,176)	(5,034)
Proceeds from sale of foreclosed assets	1,023	110	1,430
Net cash used in investing activities	(3,215,745)	(850,210)	(2,460,786)
Financing activities
Net increase in deposits	2,106,349	1,932,212	2,411,319
Costs from issuance of stock related to stock-based awards and warrants	(2,241)	(2,481)	(1,239)
Net proceeds from issuance of common stock	0	236,467	0
Preferred dividends paid	(9,750)	(9,750)	(9,750)
Net increase in other borrowings	800,000	500,000	399,995
Excess tax benefits from stock-based compensation arrangements	0	2,013	1,499
Net increase (decrease) in Federal funds purchased and repurchase agreements	255,465	(33,476)	50,375
Net cash provided by financing activities	3,149,823	2,624,985	2,852,199
Net increase in cash and cash equivalents	66,239	1,048,482	460,356
Cash and cash equivalents at beginning of period	2,839,352	1,790,870	1,330,514
Cash and cash equivalents at end of period	2,905,591	2,839,352	1,790,870
Supplemental disclosures of cash flow information:
Cash paid during the period for interest	115,789	63,193	46,078
Cash paid during the period for income taxes	103,871	88,262	87,450
Transfers from loans/leases to OREO and other repossessed assets	$ 0	$ 18,822	$ 1,267

Operations and Summary of Signi

Operations and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Operations and Summary of Significant Accounting Policies	Operations and Summary of Significant Accounting Policies Organization and Nature of Business Texas Capital Bancshares, Inc. (the "Company”), a Delaware corporation, was incorporated in November 1996 and commenced banking operations in December 1998. The consolidated financial statements of the Company include the accounts of Texas Capital Bancshares, Inc. and its wholly owned subsidiary, Texas Capital Bank, National Association (the "Bank”). We are primarily a secured lender and serve the needs of commercial businesses and successful professionals and entrepreneurs located in Texas as well as operate several lines of business serving a regional or national clientèle of commercial borrowers. We are primarily a secured lender, with our greatest concentration of loans in Texas. Basis of Presentation Our accounting and reporting policies conform to accounting principles generally accepted in the United States ("GAAP") and to generally accepted practices within the banking industry. Certain prior period balances have been reclassified to conform to the current period presentation. In that regard, ASU 2016-09, "Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting," ("ASU 2016-09") became effective for us on January 1, 2017. ASU 2016-09 requires that excess tax benefits and deficiencies be recognized as a component of income taxes within the income statement. Additionally, ASU 2016-09 requires that all income tax-related cash flows resulting from share-based payments be reported as operating activities in the statement of cash flows. Previously, income tax benefits at award settlement were reported as a reduction to operating cash flows and an increase to financing cash flows to the extent that those benefits exceeded the income tax benefits reported in earnings during the award's vesting period. We have elected to apply that change in cash flow presentation on a prospective basis. ASU 2016-09 also requires that companies make an accounting policy election regarding forfeitures, to either estimate the number of awards that are expected to vest or account for them when they occur. We have elected to recognize forfeitures as they occur. The impact of this change and that of the remaining provisions of ASU 2016-09 did not have a significant impact on our financial statements. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates. The allowance for loan losses, the allowance for off-balance sheet credit losses, the fair value of stock-based compensation awards, the fair value of mortgage servicing rights ("MSRs"), the fair value of financial instruments and the status of contingencies are particularly susceptible to significant change. Cash and Cash Equivalents Cash equivalents include amounts due from banks, interest-bearing deposits and Federal funds sold. Securities Securities are classified as trading, available-for-sale or held-to-maturity. Management classifies securities at the time of purchase and re-assesses such designation at each balance sheet date; however, transfers between categories from this re-assessment are rare. Trading Account Securities acquired for resale in anticipation of short-term market movements are classified as trading, with realized and unrealized gains and losses recognized in income. To date, we have not had any activity in our trading account. Available-for-Sale Debt securities are classified as held-to-maturity when we have the positive intent and ability to hold the securities to maturity. Held-to-maturity securities are stated at amortized cost. Debt securities not classified as held-to-maturity or trading and marketable equity securities not classified as trading are classified as available-for-sale. Available-for-sale securities are stated at fair value, with the unrealized gains and losses reported in a separate component of accumulated other comprehensive income (loss), net of tax. The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity, or in the case of mortgage-backed securities, over the estimated life of the security. Such amortization and accretion is included in interest income from securities. Realized gains and losses and declines in value judged to be other-than-temporary are included in gain (loss) on sale of securities. The cost of securities sold is based on the specific identification method. All securities are available-for-sale as of December 31, 2017 and 2016 . Loans Loans Held for Sale Through our MCA program, we commit to purchase residential mortgage loans from independent correspondent lenders and deliver those loans into the secondary market via whole loan sales to independent third parties or in securitization transactions to third parties such as Ginnie Mae or to GSEs such as Fannie Mae or Freddie Mac. In some cases, we retain the mortgage servicing rights. Once purchased, these loans are classified as held for sale and are carried at fair value pursuant to our election of the fair value option in accordance with Accounting Standards Codification 825, Financial Instruments ("ASC 825"). At the commitment date, we enter into a corresponding forward sale commitment with a third party, typically Ginnie Mae or a GSE, to deliver the loans within a specified timeframe. The estimated gain/loss for the entire transaction (from initial purchase commitment to final delivery of loans) is recorded as an asset or liability. Fair value is derived from observable current market prices, when available, and includes the fair value of the mortgage servicing rights. Adjustments to reflect unrealized gains and losses resulting from changes in fair value and realized gains and losses upon ultimate sale of the loans are classified as other non-interest income in the consolidated statements of income and other comprehensive income. Pursuant to Ginnie Mae servicing guidelines, we have the unilateral right, but not the obligation, to repurchase certain delinquent loans securitized in Ginnie Mae pools, if they meet defined delinquent loan criteria. Once the delinquency criteria have been met, and regardless of whether the repurchase option has been exercised, we account for these loans as if they had been repurchased and recognize the loans and a corresponding liability as held for sale and other liabilities, respectively, in the consolidated balance sheets. If the loans are actually repurchased, the liability is cash settled and the loans continue to be reported as held for sale. As an approved lender, we may collect losses incurred on repurchased loans through a claims process with the government agency. Loans Held for Investment Loans held for investment (which include equipment leases accounted for as financing leases) are stated at the amount of unpaid principal reduced by deferred income (net of costs). Interest on loans is recognized using the simple-interest method on the daily balances of the principal amounts outstanding. Loan origination fees, net of direct loan origination costs, and commitment fees, are deferred and amortized as an adjustment to yield over the life of the loan, or over the commitment period, as applicable. A loan held for investment is considered impaired when, based on current information and events, it is probable that we will be unable to collect all amounts due (both principal and interest) according to the terms of the loan agreement. Reserves on impaired loans are measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate or the fair value of the underlying collateral, less cost to sell. Impaired loans, or portions thereof, are charged off when a confirmed loss exists. The accrual of interest on loans is discontinued when there is a clear indication that the borrower’s cash flow may not be sufficient to meet payments as they become due, which is generally when a loan is 90 days past due. When a loan is placed on non-accrual status, all previously accrued and unpaid interest is reversed. Interest income is subsequently recognized on a cash basis as long as the remaining book balance of the asset is deemed to be collectible. If collectability is questionable, then cash payments are applied to principal. A loan is placed back on accrual status when both principal and interest are current and it is probable that we will be able to collect all amounts due (both principal and interest) according to the terms of the loan agreement. Loans held for investment includes legal ownership interests in mortgage loans that we purchase through our mortgage warehouse lending division. The ownership interests are purchased from unaffiliated mortgage originators who are seeking additional funding through sale of the undivided ownership interests to facilitate their ability to originate loans. The mortgage originator has no obligation to offer and we have no obligation to purchase these interests. The originator closes mortgage loans consistent with underwriting standards established by approved investors, and, at the time of the sale to the investor, our ownership interest and that of the originator are delivered by us to the investor selected by the originator and approved by us. We typically purchase up to a 99% ownership interest in each mortgage with the originator owning the remaining percentage. These mortgage ownership interests are generally held by us for a period of less than 30 days and more typically 10-20 days. Because of conditions in agreements with originators designed to reduce transaction risks, under ASC 860, Transfers and Servicing of Financial Assets (“ASC 860”), the ownership interests do not qualify as participating interests. Under ASC 860, the ownership interests are deemed to be loans to the originators and payments we receive from investors are deemed to be payments made by or on behalf of the originator to repay the loan deemed made to the originator. Because we have an actual, legal ownership interest in the underlying residential mortgage loan, these interests are not extensions of credit to the originators that are secured by the mortgage loans as collateral. Due to market conditions or events of default by the investor or the originator, we could be required to purchase the remaining interests in the mortgage loans and hold them beyond the expected 10-20 days. Mortgage loans acquired under these conditions would require mark-to-market adjustments to income and could require future allocations of the allowance for loan losses or be subject to charge off in the event the loans become impaired. Mortgage loan interests purchased and disposed of as expected receive no allocation of the allowance for loan losses due to the minimal loss experience with these assets. Allowance for Loan Losses The allowance for loan losses is comprised of general reserves, specific reserves for impaired loans and an additional qualitative reserve based on our estimate of losses inherent in the portfolio at the balance sheet date, but not yet identified with specified loans. We regularly evaluate our allowance for loan losses to maintain an appropriate level to absorb estimated loan losses inherent in the loan portfolio. Factors contributing to the determination of the allowance include the creditworthiness of the borrower, changes in the value of pledged collateral, and general economic conditions. All loan commitments rated substandard or worse and greater than $500,000 are specifically reviewed for loss potential. For loans deemed to be impaired, a specific allocation is assigned based on the losses expected to be realized from those loans. For purposes of determining the general reserve, the portfolio is segregated by product types to recognize differing risk profiles among categories, and then further segregated by credit grades. Credit grades are assigned to all loans. Each credit grade is assigned a risk factor, or reserve allocation percentage. These risk factors are multiplied by the outstanding principal balance and risk-weighted by product type to calculate the required reserve. A similar process is employed to calculate a reserve assigned to off-balance sheet commitments, specifically unfunded loan commitments and letters of credit, and any needed reserve is recorded in other liabilities. Even though portions of the allowance may be allocated to specific loans, the entire allowance is available for any credit that, in management’s judgment, should be charged off. We have several pass credit grades that are assigned to loans based on varying levels of risk, ranging from credits that are secured by cash or marketable securities, to watch credits which have all the characteristics of an acceptable credit risk but warrant more than the normal level of monitoring. Within our criticized/classified credit grades are special mention, substandard, and doubtful. Special mention loans are those that are currently protected by the sound worth and paying capacity of the borrower, but that are potentially weak and constitute an additional credit risk. These loans have the potential to deteriorate to a substandard grade due to the existence of financial or administrative deficiencies. Substandard loans have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They are characterized by the distinct possibility that we will sustain some loss if the deficiencies are not corrected. Some substandard loans are inappropriately protected by sound worth and paying capacity of the borrower and of the collateral pledged and may be considered impaired. Substandard loans can be accruing or can be on non-accrual depending on the circumstances of the individual loans. Loans classified as doubtful have all the weaknesses inherent in substandard loans with the added characteristics that the weaknesses make collection or liquidation in full highly questionable and improbable. The possibility of loss is extremely high. All doubtful loans are on non-accrual. The allowance allocation percentages assigned to each credit grade have been developed based primarily on an analysis of our historical loss rates. The allocations are adjusted for certain qualitative factors, including general economic conditions, changes in credit policies and lending standards. Changes in the trend and severity of problem loans can cause the estimation of losses to differ from past experience. In addition, the allowance considers the results of reviews performed by our Credit Review group as reflected in their confirmations of assigned credit grades within the portfolio. The portion of the allowance that is not derived by the allowance allocation percentages compensates for the uncertainty and complexity in estimating loan and lease losses including factors and conditions that may not be fully reflected in the determination and application of the allowance allocation percentages. Examples of risks that support the Bank's maintaining an additional qualitative reserve include economic uncertainties and unpredictable factors that produce losses, including those resulting from borrowers' submission of financial information or inaccurate certification of collateral values. These situations, while not common, do not necessarily correlate well with historical loss trends or general economic conditions. Our methodology used to calculate the allowance considers historical losses, however, the historical loss rates for specific product types or credit risk grades may not fully incorporate the effects of uncertainty regarding the economy or other unpredictable events. The methodology used in the periodic review of the appropriateness of the allowance, which is performed at least quarterly, is designed to be dynamic and responsive to changes in portfolio credit quality. The changes are reflected in the general allowance and in specific reserves as the collectability of classified loans is evaluated with new information. As our portfolio has matured, historical loss ratios have been closely monitored, and our reserve appropriateness relies primarily on our loss history. The review of the appropriateness of the allowance is performed by executive management and presented to the audit and risk committees of our board of directors for their review. The committees report to the board as part of the board's review on a quarterly basis of the Company's consolidated financial statements. Other Real Estate Owned Other real estate owned (“OREO”), which is included in other assets on the consolidated balance sheet, consists of real estate that has been foreclosed. Real estate that has been foreclosed is recorded at the fair value of the real estate, less selling costs, through a charge to the allowance for loan losses, if necessary. Subsequent write-downs required for declines in value are recorded through a valuation allowance, or taken directly to the asset, charged to other non-interest expense. Premises and Equipment Premises and equipment are stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which range from three to ten years . Gains or losses on disposals of premises and equipment are included in other non-interest income in the consolidated income statements. Marketing and Software Marketing costs are expensed as incurred. Ongoing maintenance and enhancements of websites are expensed as incurred. Costs incurred in connection with development or purchase of internal use software are capitalized and amortized over a period not to exceed five years . Internal use software costs are included in other assets in the consolidated balance sheets. Goodwill and Other Intangible Assets Intangible assets are acquired assets that lack physical substance but can be distinguished from goodwill because of contractual or other legal rights or because the asset is capable of being sold or exchanged either on its own or in combination with a related contract, asset, or liability. Our intangible assets relate primarily to loan customer relationships. Intangible assets with definite useful lives are amortized over their estimated life. Goodwill and intangible assets are tested for impairment in October on an annual basis or whenever events or changes in circumstances indicate the carrying amount of the assets may not be recoverable from future undiscounted cash flows. If impaired, the assets are recorded at fair value. Segment Reporting We have determined that all of our lending divisions and subsidiaries meet the aggregation criteria of ASC 280, Segment Reporting , since all offer similar products and services, operate with similar processes, and have similar customers. Stock-based Compensation We account for all stock-based compensation transactions in accordance with ASC 718, Compensation — Stock Compensation (“ASC 718”), which requires that stock compensation transactions be recognized as compensation expense in the consolidated statement of income and other comprehensive income based on their fair values on the measurement date, which is the date of the grant. Accumulated Other Comprehensive Income Unrealized gains or losses on our available-for-sale securities (after applicable income tax expense or benefit) are included in accumulated other comprehensive income, net. Accumulated other comprehensive income (loss), net is reported in the accompanying consolidated statements of stockholders’ equity and consolidated statements of income and other comprehensive income. Income Taxes The Company and its subsidiary file a consolidated federal income tax return. We utilize the liability method in accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based upon the difference between the values of the assets and liabilities as reflected in the financial statements and their related tax basis using enacted tax rates in effect for the year in which the differences are expected to be recovered or settled. As changes in tax law or rates are enacted, deferred tax assets and liabilities are adjusted through the provision for income taxes. A valuation allowance is provided against deferred tax assets unless it is more likely than not that such deferred tax assets will be realized. Basic and Diluted Earnings Per Common Share Basic earnings per common share is based on net income available to common stockholders divided by the weighted-average number of common shares outstanding during the period excluding non-vested stock. Diluted earnings per common share include the dilutive effect of stock options and non-vested stock awards granted using the treasury stock method. A reconciliation of the weighted-average shares used in calculating basic earnings per common share and the weighted average common shares used in calculating diluted earnings per common share for the reported periods is provided in Note 15 — Earnings Per Share. Fair Values of Financial Instruments ASC 820, Fair Value Measurements and Disclosures (“ASC 820”), defines fair value, establishes a framework for measuring fair value under GAAP and enhances disclosures about fair value measurements. In general, fair values of financial instruments are based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based on estimates using present value or other valuation techniques. Those techniques are significantly affected by the assumptions used, including the discount rate and estimates of future cash flows. Mortgage Servicing Rights Mortgage servicing rights are created by selling purchased or originated mortgage loans with servicing rights retained. We identify classes of servicing rights based upon the nature of the underlying assumptions used to value the asset along with the risks associated with the underlying asset. Based upon these criteria we have one class of MSRs, residential. Originated MSRs are recognized based on the estimated fair value of the mortgage loans and the related servicing rights at the date of sale using values derived from a valuation model managed by an independent third party. MSRs are amortized proportionally over the estimated life of the projected net servicing revenue and are periodically evaluated for impairment. MSRs are reported on the consolidated balance sheets at amortized cost, less a valuation allowance if the fair value of identified strata within the MSR portfolio are determined to have a fair value that is less than amortized cost. Loan servicing fee income represents income earned for servicing mortgage loans owned by investors and includes mortgage servicing fees and other ancillary servicing income. Servicing fees are recorded as income when earned and are reported in other non-interest income on the consolidated statements of income and other comprehensive income. For additional information on MSRs, see Note 5 - Certain Transfers of Financial Assets. Financial Instruments with Off-Balance Sheet Risk The Company has undertaken certain guarantee obligations in the ordinary course of business which include liabilities with off-balance sheet risk. We consider the following arrangements to be guarantees: commitments to extend credit, standby letters of credit and indemnification agreements included within third party contractual arrangements. For additional information on commitments and contingencies, see Note 13 - Financial Instruments with Off-Balance Sheet Risk. Derivative Financial Instruments All contracts that satisfy the definition of a derivative are recorded at fair value in other assets and other liabilities in the consolidated balance sheets. We record the derivatives on a net basis when a right of offset exists, based on transactions with a single counterparty that are subject to a legally enforceable master netting agreement. For additional information on derivative financial instruments, see Note 20 - Derivative Financial Instruments.

Securities

Securities	12 Months Ended
	Dec. 31, 2017
Available-for-sale Securities [Abstract]
Securities	Securities The following is a summary of securities (in thousands): December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Available-for-sale securities: Residential mortgage-backed securities $ 10,297 $ 648 $ — $ 10,945 Equity securities(1) 12,556 425 (415 ) 12,566 $ 22,853 $ 1,073 $ (415 ) $ 23,511 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Available-for-sale securities: Residential mortgage-backed securities $ 14,680 $ 972 $ — $ 15,652 Municipals 275 — — 275 Equity securities(1) 9,280 27 (360 ) 8,947 $ 24,235 $ 999 $ (360 ) $ 24,874 (1) Equity securities consist of Community Reinvestment Act funds and investments related to our non-qualified deferred compensation plan. The amortized cost and estimated fair value of securities are presented below by contractual maturity (in thousands, except percentage data): December 31, 2017 Less Than One Year After One Through Five Years After Five Through Ten Years After Ten Years Total Available-for-sale: Residential mortgage-backed securities:(1) Amortized cost $ 409 $ 819 $ 1,502 $ 7,567 $ 10,297 Estimated fair value 418 916 1,636 7,975 10,945 Weighted average yield(3) 4.59 % 6.02 % 5.32 % 3.45 % 3.97 % Equity securities:(4) Amortized cost 12,556 — — — 12,556 Estimated fair value 12,566 — — — 12,566 Total available-for-sale securities: Amortized cost $ 22,853 Estimated fair value $ 23,511 December 31, 2016 Less Than One Year After One Through Five Years After Five Through Ten Years After Ten Years Total Available-for-sale: Residential mortgage-backed securities:(1) Amortized cost $ 9 $ 2,047 $ 3,147 $ 9,477 $ 14,680 Estimated fair value 9 2,104 3,495 10,044 15,652 Weighted average yield(3) 5.50 % 4.70 % 5.55 % 2.84 % 3.68 % Municipals:(2) Amortized cost 275 — — — 275 Estimated fair value 275 — — — 275 Weighted average yield(3) 5.61 % — — — 5.61 % Equity securities:(4) Amortized cost 9,280 — — — 9,280 Estimated fair value 8,947 — — — 8,947 Total available-for-sale securities: Amortized cost $ 24,235 Estimated fair value $ 24,874 (1) Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without prepayment penalties. (2) Yields have been adjusted to a tax equivalent basis assuming a 35% federal tax rate. (3) Yields are calculated based on amortized cost. (4) These equity securities do not have a stated maturity. Securities with carrying values of approximately $8.8 million and $13.6 million were pledged to secure certain borrowings and deposits at December 31, 2017 and 2016 , respectively. See Note 9 — Borrowing Arrangements for discussion of securities securing borrowings. Of the pledged securities at December 31, 2017 and 2016 , approximately $1.6 million and $3.4 million , respectively, were pledged for certain deposits. The following table discloses, as of December 31, 2017 and December 31, 2016 , our investment securities that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for 12 or more months (in thousands): December 31, 2017 Less Than 12 Months 12 Months or Longer Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Equity securities $ 1,015 $ (6 ) $ 6,091 $ (409 ) $ 7,106 $ (415 ) December 31, 2016 Less Than 12 Months 12 Months or Longer Total Fair Unrealized Fair Unrealized Fair Unrealized Equity securities $ 1,015 $ (6 ) $ 6,146 $ (354 ) $ 7,161 $ (360 ) At December 31, 2017 and December 31, 2016 , we owned two securities with an unrealized loss position. These securities are publicly traded equity funds and are subject to market pricing volatility. We do not believe that this unrealized loss is “other than temporary.” We have evaluated the near-term prospects of the investments in relation to the severity and duration of the impairment and based on that evaluation have the ability and intent to hold the investments until recovery of fair value. Unrealized gains or losses on our available-for-sale securities (after applicable income tax expense or benefit) are included in accumulated other comprehensive income, net.

Loans and Allowance for Credit

Loans and Allowance for Credit Losses	12 Months Ended
	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Loans and Allowance for Credit Losses	Loans Held for Investment and Allowance for Loan Losses Loans held for investment are summarized by category as follows (in thousands): December 31, 2017 2016 Commercial $ 9,189,811 $ 7,291,545 Mortgage finance 5,308,160 4,497,338 Construction 2,166,208 2,098,706 Real estate 3,794,577 3,462,203 Consumer 48,684 34,587 Equipment leases 264,903 185,529 Gross loans held for investment 20,772,343 17,569,908 Deferred income (net of direct origination costs) (97,931 ) (71,559 ) Allowance for loan losses (184,655 ) (168,126 ) Total loans held for investment $ 20,489,757 $ 17,330,223 Commercial Loans and Leases. Our commercial loan portfolio is comprised of lines of credit for working capital and term loans and leases to finance equipment and other business assets. Our energy production loans are generally collateralized with proven reserves based on appropriate valuation standards and take into account the risk of oil and gas price volatility. Our commercial loans and leases are underwritten after carefully evaluating and understanding the borrower’s ability to operate profitably. Our underwriting standards are designed to promote relationship banking rather than to make loans on a transaction basis. Our lines of credit typically are limited to a percentage of the value of the assets securing the line. Lines of credit and term loans typically are reviewed annually, or more frequently, as needed, and are supported by accounts receivable, inventory, equipment and other assets of our clients’ businesses. Mortgage Finance Loans. Our mortgage finance loans consist of ownership interests purchased in single-family residential mortgages funded through our mortgage warehouse lending division. We have agreements with mortgage lenders and purchase interests in individual loans they originate. The ownership interests collateralizing our mortgage finance loans are typically held on our balance sheet for 10 to 20 days, and substantially all loans are conforming loans. All mortgage finance loans are underwritten consistently with established programs for permanent financing with financially sound investors. Balances as of December 31, 2017 and 2016 are stated net of $171.2 million and $839.0 million participations sold, respectively. Construction Loans. Our construction loan portfolio consists primarily of single- and multi-family residential properties and commercial projects used in manufacturing, warehousing, service or retail businesses. Our construction loans generally have terms of one to three years . We typically make construction loans to developers, builders and contractors that have an established record of successful project completion and loan repayment and have a substantial equity investment in the borrowers. Loan amounts are derived primarily from the Bank's evaluation of expected cash flows available to service debt from stabilized projects under hypothetically stressed conditions. Construction loans are also based in part upon estimates of costs and value associated with the completed project. Sources of repayment for these types of loans may be permanent loans from other lenders, sales of developed property, or an interim loan commitment from us until permanent financing is obtained. The nature of these loans makes ultimate repayment sensitive to overall economic conditions. Borrowers may not be able to correct conditions of default in loans, increasing risk of exposure to classification, non-performing status, reserve allocation and actual credit loss and foreclosure. These loans typically have floating rates and require commitment fees. Real Estate Loans. A portion of our real estate loan portfolio is comprised of loans secured by properties other than market risk or investment-type real estate. Market risk loans are real estate loans where the primary source of repayment is expected to come from the sale, permanent financing or lease of the real property collateral. We generally provide temporary financing for commercial and residential property. These loans are viewed primarily as cash flow loans and secondarily as loans secured by real estate. Our real estate loans generally have maximum terms of five to seven years , and we provide loans with both floating and fixed rates. Real estate loans may be more adversely affected by conditions in the real estate markets or in the general economy. Appraised values may be highly variable due to market conditions and the impact of the inability of potential purchasers and lessees to obtain financing and a lack of transactions at comparable values. At December 31, 2017 and 2016 , we had a blanket floating lien on certain real estate-secured loans, mortgage finance loans and also certain securities used as collateral for FHLB borrowings. Summary of Loan Losses The allowance for loan losses is comprised of general reserves, specific reserves for impaired loans and an additional qualitative reserve based on our estimate of losses inherent in the portfolio at the balance sheet date, but not yet identified with specified loans. We believe the allowance at December 31, 2017 to be appropriate, given management's assessment of losses inherent in the portfolio as of the evaluation date, the significant growth in the loan and lease portfolio, current economic conditions in our market areas and other factors. The following tables summarize the credit risk profile of our loan portfolio by internally assigned grades and non-accrual status as of December 31, 2017 and 2016 (in thousands): Commercial Mortgage Finance Construction Real Estate Consumer Equipment Leases Total December 31, 2017 Grade: Pass $ 8,967,471 $ 5,308,160 $ 2,152,654 $ 3,706,541 $ 48,591 $ 249,865 $ 20,433,282 Special mention 19,958 — 13,554 53,652 — 495 87,659 Substandard- accruing 102,651 — — 32,671 93 14,543 149,958 Non-accrual 99,731 — — 1,713 — — 101,444 Total loans held for investment $ 9,189,811 $ 5,308,160 $ 2,166,208 $ 3,794,577 $ 48,684 $ 264,903 $ 20,772,343 Commercial Mortgage Finance Construction Real Estate Consumer Equipment Leases Total December 31, 2016 Grade: Pass $ 6,941,310 $ 4,497,338 $ 2,074,859 $ 3,430,346 $ 34,249 $ 181,914 $ 17,160,016 Special mention 69,447 — 10,901 21,932 — 3,532 105,812 Substandard-accruing 115,848 — 12,787 7,516 138 — 136,289 Non-accrual 164,940 — 159 2,409 200 83 167,791 Total loans held for investment $ 7,291,545 $ 4,497,338 $ 2,098,706 $ 3,462,203 $ 34,587 $ 185,529 $ 17,569,908 The following tables detail activity in the allowance for loan losses by portfolio segment for the years ended December 31, 2017 and 2016 (in thousands). Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories. Commercial Mortgage Finance Construction Real Estate Consumer Equipment Leases Additional Qualitative Reserve Total December 31, 2017 Allowance for loan losses Beginning balance $ 128,768 $ — $ 13,144 $ 19,149 $ 241 $ 1,124 $ 5,700 $ 168,126 Provision for loan losses 19,590 — 6,084 15,353 226 2,408 2,690 46,351 Charge-offs 34,145 — 59 290 180 — — 34,674 Recoveries 4,593 — 104 75 70 10 — 4,852 Net charge-offs (recoveries) 29,552 — (45 ) 215 110 (10 ) — 29,822 Ending balance $ 118,806 $ — $ 19,273 $ 34,287 $ 357 $ 3,542 $ 8,390 $ 184,655 Period end amount allocated to: Loans individually evaluated for impairment $ 24,316 $ — $ — $ 101 $ — $ — $ — $ 24,417 Loans collectively evaluated for impairment 94,490 — 19,273 34,186 357 3,542 8,390 160,238 Ending balance $ 118,806 $ — $ 19,273 $ 34,287 $ 357 $ 3,542 $ 8,390 $ 184,655 Commercial Mortgage Finance Construction Real Estate Consumer Equipment Leases Additional Qualitative Reserve Total December 31, 2016 Allowance for loan losses Beginning balance $ 112,446 $ — $ 6,836 $ 13,381 $ 338 $ 3,931 $ 4,179 $ 141,111 Provision for loan losses 63,516 — 6,274 6,233 (71 ) (2,884 ) 1,521 74,589 Charge-offs 56,558 — — 528 47 — — 57,133 Recoveries 9,364 — 34 63 21 77 — 9,559 Net charge-offs (recoveries) 47,194 — (34 ) 465 26 (77 ) — 47,574 Ending balance $ 128,768 $ — $ 13,144 $ 19,149 $ 241 $ 1,124 $ 5,700 $ 168,126 Period end amount allocated to: Loans individually evaluated for impairment $ 34,405 $ — $ 24 $ 133 $ 30 $ 13 $ — $ 34,605 Loans collectively evaluated for impairment 94,363 — 13,120 19,016 211 1,111 5,700 133,521 Ending balance $ 128,768 $ — $ 13,144 $ 19,149 $ 241 $ 1,124 $ 5,700 $ 168,126 The table below presents the activity in the allowance for off-balance sheet credit losses related to losses on unfunded commitments for the years ended December 31, 2017 and 2016 (in thousands). This allowance is recorded in other liabilities in the consolidated balance sheet. Year Ended December 31, 2017 2016 Beginning balance $ 11,422 $ 9,011 Provision for off-balance sheet credit losses (2,351 ) 2,411 Ending balance $ 9,071 $ 11,422 We have traditionally maintained an additional qualitative reserve component to compensate for the uncertainty and complexity in estimating loan and lease losses including factors and conditions that may not be fully reflected in the determination and application of the allowance allocation percentages. The increase in the additional qualitative reserve at December 31, 2017 was primarily driven by a $4.5 million provision in the third quarter of 2017 reflecting our assessment of the potential impact to our loan portfolio from Hurricanes Harvey and Irma. We believe the level of additional qualitative reserves at December 31, 2017 is warranted due to economic uncertainties and unpredictable factors that have produced losses, including those resulting from borrowers' misstatement of financial information or inaccurate certification of collateral values. Such losses are not necessarily correlated with historical loss trends or general economic conditions. Our methodology used to calculate the allowance considers historical losses; however, the historical loss rates for specific product types or credit risk grades may not fully incorporate the effects of uncertainty regarding the economy or other unpredictable events. Our recorded investment in loans as of December 31, 2017 and 2016 related to each balance in the allowance for loan losses by portfolio segment and disaggregated on the basis of our impairment methodology was as follows (in thousands): Commercial Mortgage Finance Construction Real Estate Consumer Equipment Leases Total December 31, 2017 Loans individually evaluated for impairment $ 100,676 $ — $ — $ 2,008 $ — $ — $ 102,684 Loans collectively evaluated for impairment 9,089,135 5,308,160 2,166,208 3,792,569 48,684 264,903 20,669,659 Total $ 9,189,811 $ 5,308,160 $ 2,166,208 $ 3,794,577 $ 48,684 $ 264,903 $ 20,772,343 Commercial Mortgage Finance Construction Real Estate Consumer Equipment Leases Total December 31, 2016 Loans individually evaluated for impairment $ 166,669 $ — $ 159 $ 3,751 $ 200 $ 83 $ 170,862 Loans collectively evaluated for impairment 7,124,876 4,497,338 2,098,547 3,458,452 34,387 185,446 17,399,046 Total $ 7,291,545 $ 4,497,338 $ 2,098,706 $ 3,462,203 $ 34,587 $ 185,529 $ 17,569,908 Generally we place loans on non-accrual when there is a clear indication that the borrower’s cash flow may not be sufficient to meet payments as they become due, which is generally when a loan is 90 days past due. When a loan is placed on non-accrual status, all previously accrued and unpaid interest is reversed. Interest income is subsequently recognized on a cash basis as long as the remaining unpaid principal amount of the loan is deemed to be fully collectible. If collectability is questionable, then cash payments are applied to principal. We recognized $1.3 million in interest income on non-accrual loans during 2017 compared to $1.4 million in 2016 and $1.6 million in 2015 . Additional interest income that would have been recorded if the loans had been current during the years ended December 31, 2017 , 2016 and 2015 totaled $19.0 million , $7.9 million and $7.0 million , respectively. As of December 31, 2017 , none of our non-accrual loans were earning on a cash basis, compared to $811,000 at December 31, 2016 . A loan is placed back on accrual status when both principal and interest are current and it is probable that we will be able to collect all amounts due (both principal and interest) according to the terms of the loan agreement. A loan held for investment is considered impaired when, based on current information and events, it is probable that we will be unable to collect all amounts due (both principal and interest) according to the terms of the original loan agreement. In accordance with ASC 310, Receivables , we have also included all restructured and formerly restructured loans in our impaired loan totals. The following tables detail our impaired loans, by portfolio class, as of December 31, 2017 and 2016 (in thousands): December 31, 2017 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized With no related allowance recorded: Commercial Business loans $ 16,835 $ 18,257 $ — $ 22,964 $ — Energy loans 21,426 22,602 — 36,579 — Construction Market risk — — — — — Real estate Market risk — — — — — Commercial 1,096 1,096 — 2,166 — Secured by 1-4 family — — — — — Consumer — — — — — Equipment leases — — — — — Total impaired loans with no allowance recorded $ 39,357 $ 41,955 $ — $ 61,709 $ — With an allowance recorded: Commercial Business loans $ 18,645 $ 19,020 $ 2,544 $ 16,960 $ — Energy loans 43,770 55,875 21,772 50,867 6 Construction Market risk — — — 27 — Real estate Market risk 295 295 6 485 — Commercial 499 499 75 166 — Secured by 1-4 family 118 118 20 516 — Consumer — — — 33 — Equipment leases — — — 14 — Total impaired loans with an allowance recorded $ 63,327 $ 75,807 $ 24,417 $ 69,068 $ 6 Combined: Commercial Business loans $ 35,480 $ 37,277 $ 2,544 $ 39,924 $ — Energy loans 65,196 78,477 21,772 87,446 6 Construction Market risk — — — 27 — Real estate Market risk 295 295 6 485 — Commercial 1,595 1,595 75 2,332 — Secured by 1-4 family 118 118 20 516 — Consumer — — — 33 — Equipment leases — — — 14 — Total impaired loans $ 102,684 $ 117,762 $ 24,417 $ 130,777 $ 6 December 31, 2016 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized With no related allowance recorded: Commercial Business loans $ 23,868 $ 27,992 $ — $ 12,361 $ — Energy loans 46,753 54,522 — 54,075 — Construction Market risk — — — 2,778 — Real estate Market risk — — — — — Commercial 2,083 2,083 — 4,483 38 Secured by 1-4 family — — — — — Consumer — — — — — Equipment leases — — — 403 — Total impaired loans with no allowance recorded $ 72,704 $ 84,597 $ — $ 74,100 $ 38 With an allowance recorded: Commercial Business loans $ 21,303 $ 21,303 $ 7,055 $ 22,277 $ — Energy loans 74,745 88,987 27,350 73,637 24 Construction Market risk 159 159 24 53 — Real estate Market risk 1,342 1,342 20 3,000 — Commercial — — — — — Secured by 1-4 family 326 326 113 435 — Consumer 200 200 30 67 — Equipment leases 83 83 13 548 — Total impaired loans with an allowance recorded $ 98,158 $ 112,400 $ 34,605 $ 100,017 $ 24 Combined: Commercial Business loans $ 45,171 $ 49,295 $ 7,055 $ 34,638 $ — Energy loans 121,498 143,509 27,350 127,712 24 Construction Market risk 159 159 24 2,831 — Real estate Market risk 1,342 1,342 20 3,000 — Commercial 2,083 2,083 — 4,483 38 Secured by 1-4 family 326 326 113 435 — Consumer 200 200 30 67 — Equipment leases 83 83 13 951 — Total impaired loans $ 170,862 $ 196,997 $ 34,605 $ 174,117 $ 62 Average impaired loans outstanding during the years ended December 31, 2017 , 2016 and 2015 totaled $130.8 million , $174.1 million and $102.3 million , respectively. The table below provides an age analysis of our loans held for investment as of December 31, 2017 (in thousands): 30-59 Days Past Due 60-89 Days Past Due Greater Than 90 Days(1) Total Past Due Non-accrual Current Total Commercial Business loans $ 12,346 $ 13,029 $ 6,984 $ 32,359 $ 34,535 $ 7,992,918 $ 8,059,812 Energy 1,100 — — 1,100 65,196 1,063,703 1,129,999 Mortgage finance loans — — — — — 5,308,160 5,308,160 Construction Market risk 239 — — 239 — 2,098,446 2,098,685 Commercial — — — — — 35,786 35,786 Secured by 1-4 family 1,635 — — 1,635 — 30,102 31,737 Real estate Market risk 1,724 295 — 2,019 — 2,681,527 2,683,546 Commercial — — — — 1,595 839,787 841,382 Secured by 1-4 family 174 139 1,392 1,705 118 267,826 269,649 Consumer 100 74 — 174 — 48,510 48,684 Equipment leases 636 16 53 705 — 264,198 264,903 Total loans held for investment $ 17,954 $ 13,553 $ 8,429 $ 39,936 $ 101,444 $ 20,630,963 $ 20,772,343 (1) Loans past due 90 days and still accruing includes premium finance loans of $5.5 million . These loans are generally secured by obligations of insurance carriers to refund premiums on canceled insurance policies. The refund of premiums from the insurance carriers can take 180 days or longer from the cancellation date. Restructured loans are loans on which, due to the borrower’s financial difficulties, we have granted a concession that we would not otherwise consider for borrowers of similar credit quality. This may include a transfer of real estate or other assets from the borrower, a modification of loan terms, or a combination of the two. Modifications of terms that could potentially qualify as a restructuring include reduction of contractual interest rate, extension of the maturity date at a contractual interest rate lower than the current rate for new debt with similar risk, or a reduction of the face amount of debt, or forgiveness of either principal or accrued interest. As of December 31, 2017 and December 31, 2016 , we did not have any loans considered restructured that were not on non-accrual. Of the non-accrual loans at December 31, 2017 and 2016 , $18.8 million and $18.1 million , respectively, met the criteria for restructured. These loans had no unfunded commitments at their respective balance sheet dates. A loan continues to qualify as restructured until a consistent payment history or change in borrower’s financial condition has been evidenced, generally no less than twelve months. Assuming that the restructuring agreement specifies an interest rate at the time of the restructuring that is greater than or equal to the rate that we are willing to accept for a new extension of credit with comparable risk, then the loan no longer has to be considered a restructuring if it is in compliance with modified terms in calendar years after the year of the restructure. The following tables summarize, as of December 31, 2017 and 2016 , loans that have been restructured during 2017 and 2016 (in thousands, except number of contracts): December 31, 2017 Number of Contracts Pre-Restructuring Outstanding Recorded Investment Post-Restructuring Outstanding Recorded Investment Commercial business loans 3 $ 7,527 $ 7,640 Energy loans 1 $ 1,070 $ — Total new restructured loans in 2017 4 $ 8,597 $ 7,640 December 31, 2016 Number of Contracts Pre-Restructuring Outstanding Recorded Investment Post-Restructuring Outstanding Recorded Investment Energy loans 2 $ 14,235 $ 12,236 Total new restructured loans in 2016 2 $ 14,235 $ 12,236 The restructured loans generally include terms to temporarily place the loan on interest only, extend the payment terms or reduce the interest rate. We did not forgive any principal on the above loans. The $957,000 decrease in the post-restructuring recorded investment in 2017 and the $2.0 million decrease in the post-restructuring recorded investment in 2016 were due to paydowns. At December 31, 2017 , $7.6 million of the above loans restructured in 2017 are on non-accrual. The restructuring of the loans did not have a significant impact on our allowance for loan losses at December 31, 2017 or 2016 . The following table provides information on how loans were modified as restructured loans during the year ended December 31, 2017 and 2016 (in thousands): December 31, 2017 2016 Extended maturity $ 712 $ — Adjusted payment schedule 6,928 — Combination of maturity extension and payment schedule adjustment — 12,236 Total $ 7,640 $ 12,236 As of December 31, 2017 and 2016 , we did not have any loans that were restructured within the last 12 months that subsequently defaulted.

OREO and Valuation Allowance fo

OREO and Valuation Allowance for Losses on OREO	12 Months Ended
	Dec. 31, 2017
Real Estate Owned, Disclosure of Detailed Components [Abstract]
OREO and Valuation Allowance for Losses on OREO	OREO and Valuation Allowance for Losses on OREO The table below presents a summary of the activity related to OREO (in thousands): Year ended December 31, 2017 2016 2015 Beginning balance $ 18,961 $ 278 $ 568 Additions — 18,822 1,267 Sales (1,108 ) (139 ) (1,557 ) Valuation allowance for OREO — — — Direct write-downs (6,111 ) — — Ending balance $ 11,742 $ 18,961 $ 278 When foreclosure occurs, the acquired asset is recorded at fair value less selling costs, generally based on appraised value, which may result in partial charge-off of the loan. Subsequent write-downs required for declines in value are recorded through a valuation allowance or taken directly against the asset and charged to other non-interest expense. During 2017, we recorded a $6.1 million write-down on one asset.

Certain Transfers of Financial

Certain Transfers of Financial Assets	12 Months Ended
	Dec. 31, 2017
Transfers and Servicing [Abstract]
Certain Transfers of Financial Assets	Certain Transfers of Financial Assets Through our MCA business, we commit to purchase residential mortgage loans from independent correspondent lenders and deliver those loans into the secondary market via whole loans sales to independent third parties or in securitization transactions to Ginnie Mae and GSEs such as Fannie Mae and Freddie Mac. We have elected to carry these loans at fair value based on sales commitments and market quotes. Gains and losses on the sale of mortgage loans held for sale and changes in the fair value of the loans held for sale are included in other non-interest income on the consolidated income statement. Residential mortgage loans held for sale are subject to both credit and interest rate risk. Credit risk is managed through underwriting policies and procedures, including collateral requirements, which are generally accepted by the secondary loan markets. Exposure to interest rate fluctuations is partially managed through forward sales contracts, which set the price for loans that will be delivered in the next 60 to 90 days. The table below presents the unpaid principal balance of loans held for sale and related fair values at December 31, 2017 and 2016 (in thousands): December 31, 2017 2016 Outstanding balance(1) $ 1,009,271 $ 980,414 Fair value(1) 1,007,695 968,929 Fair value over (under) outstanding balance $ (1,576 ) $ (11,485 ) (1) Does not include $3.3 million of Small Business Administration ("SBA") loans held for sale carried at lower of cost or market as of December 31, 2017 . No loans held for sale were on non-accrual as of December 31, 2017 or December 31, 2016 . At December 31, 2017 , we had $19.7 million in loans held for sale that were 90 days or more past due, compared to no ne at December 31, 2016 . Of this $19.7 million , $19.0 million are loans with government guarantees that we purchased and sold into securitized Ginnie Mae pools. Pursuant to Ginnie Mae servicing guidelines, we have the unilateral right, but not the obligation, to repurchase these loans if they meet defined delinquent loan criteria, and therefore must record any delinquent loans as held for sale on our balance sheet regardless of whether the repurchase option has been exercised. The table below presents a reconciliation of the changes in loans held for sale for the years December 31, 2017 and 2016 (in thousands): Year Ended December 31, 2017 2016 Beginning balance $ 968,929 $ 86,075 Loans purchased 5,556,964 3,327,482 Payments and loans sold (5,524,798 ) (2,433,348 ) Change in fair value 9,909 (11,280 ) Ending balance(1) $ 1,011,004 $ 968,929 (1) Includes $3.3 million of SBA loans held for sale carried at lower of cost or market at December 31, 2017 . We generally retain the right to service the loans sold, creating MSRs which are recorded as assets on our balance sheet. A summary of MSR activity for the years ended December 31, 2017 and 2016 is as follows (in thousands): Year Ended December 31, 2017 2016 MSRs: Balance, beginning of year $ 28,536 $ 423 Capitalized servicing rights 67,970 29,816 Amortization (8,356 ) (1,703 ) Balance, end of period $ 88,150 $ 28,536 Valuation allowance: Balance, beginning of year $ — $ — Increase in valuation allowance 2,823 — Balance, end of period $ 2,823 $ — MSRs, net(1) $ 85,327 $ 28,536 MSRs, fair value $ 86,321 $ 30,877 (1) MSRs are reported on the consolidated balance sheets at amortized cost. At December 31, 2017 and 2016 , our servicing portfolio of residential mortgage loans had an outstanding principal balance of $7.0 billion and $2.2 billion , respectively. In connection with the servicing of these loans, we hold deposits in the name of investors representing escrow funds for taxes and insurance, as well as collections in transit to investors. These escrow funds are segregated and held in separate non-interest-bearing bank accounts at the Bank. These deposits, included in total non-interest-bearing deposits on the consolidated balance sheets, were $73.4 million at December 31, 2017 and $21.0 million at December 31, 2016 . The estimated fair value of the MSR assets is obtained from an independent third party and reviewed by management on a quarterly basis. MSRs typically do not trade in an active, open market with readily observable prices; as such, the fair value of MSRs is determined using a discounted cash flow model to calculate the present value of the estimated future net servicing income. The assumptions utilized in the discounted cash flow model are based on market data for comparable assets, where available. Each quarter, management and the independent third party discuss the key assumptions used in the discounted cash flow model and make adjustments as necessary to estimate the fair value of the MSRs. At December 31, 2017 , the estimated fair value of MSRs was adjusted in anticipation of a sale of Ginnie Mae MSRs in the first quarter of 2018, which resulted in a $2.8 million impairment charge. As of December 31, 2017 and December 31, 2016 , management used the following assumptions to determine the fair value of MSRs: December 31, 2017 2016 Average discount rates 9.90 % 9.96 % Expected prepayment speeds 9.99 % 7.91 % Weighted-average life, in years 7.0 8.0 A sensitivity analysis of changes in the fair value of our MSR portfolio resulting from certain key assumptions is presented in the following table (in thousands): December 31, 2017 2016 50 bp adverse change in prepayment speed $ (11,896 ) $ (2,833 ) 100 bp adverse change in prepayment speed (28,226 ) (6,812 ) These sensitivities are hypothetical and actual results may differ materially due to a number of factors. The effect on fair value of a 10% variation in assumptions generally cannot be determined with confidence because the relationship of the change in assumptions to the fair value may not be linear. Additionally, the impact of a variation in a particular assumption on the fair value is calculated while holding other assumptions constant. In reality, changes in one factor may be correlated with changes in other factors, which could impact the sensitivity analysis as presented. In conjunction with the sale and securitization of loans held for sale, we may be exposed to liability resulting from recourse agreements and repurchase agreements. If it is determined subsequent to our sale of a loan that the loan sold is in breach of the representations or warranties made in the applicable sale agreement, we may have an obligation to either (a) repurchase the loan for the unpaid principal balance, accrued interest and related advances, (b) indemnify the purchaser against any loss it suffers or (c) make the purchaser whole for the economic benefits of the loan. Our repurchase, indemnification and make whole obligations vary based upon the terms of the applicable agreements, the nature of the asserted breach and the status of the mortgage loan at the time a claim is made. We establish reserves for estimated losses of this nature inherent in the origination of mortgage loans by estimating the losses inherent in the population of all loans sold based on trends in claims and actual loss severities experienced. The reserve will include accruals for probable contingent losses in addition to those identified in the pipeline of claims received. The estimation process is designed to include amounts based on actual losses experienced from actual repurchase activity. Our estimated exposure related to loans previously sold was $1.3 million at December 31, 2017 and $835,000 at December 31, 2016 and is recorded in other liabilities in the consolidated balance sheets. We incurred $ 31,000 in losses due to repurchase, indemnification and make-whole obligations during the year ended December 31, 2017 compared to no ne in 2016 .

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill and other intangible assets at December 31, 2017 and 2016 are summarized as follows (in thousands): Gross Goodwill and Intangible Assets Accumulated Amortization Net Goodwill and Intangible Assets December 31, 2017 Goodwill $ 15,468 $ (374 ) $ 15,094 Intangible assets—customer relationships and trademarks 9,006 (5,060 ) 3,946 Total goodwill and intangible assets $ 24,474 $ (5,434 ) $ 19,040 December 31, 2016 Goodwill $ 15,468 $ (374 ) $ 15,094 Intangible assets—customer relationships and trademarks 9,006 (4,588 ) 4,418 Total goodwill and intangible assets $ 24,474 $ (4,962 ) $ 19,512 Amortization expense related to intangible assets totaled $472,000 in 2017 , $448,000 in 2016 and $628,000 in 2015 . The estimated aggregate future amortization expense for intangible assets remaining as of December 31, 2017 is as follows (in thousands): 2018 $ 470 2019 470 2020 432 2021 405 2022 405 Thereafter 1,764 $ 3,946

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Premises and Equipment	Premises and Equipment Premises and equipment at December 31, 2017 and 2016 are summarized as follows (in thousands): December 31, 2017 2016 Premises $ 25,790 $ 22,887 Furniture and equipment 32,234 24,159 58,024 47,046 Accumulated depreciation (32,848 ) (27,271 ) Total premises and equipment, net $ 25,176 $ 19,775 Depreciation expense for the above premises and equipment was approximately $6.9 million, $6.0 million and $4.6 million in 2017 , 2016 and 2015 , respectively.

Deposits

Deposits	12 Months Ended
	Dec. 31, 2017
Deposits [Abstract]
Deposits	Deposits Deposits at December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Non-interest-bearing demand deposits $ 7,812,660 $ 7,994,201 Interest-bearing deposits Transaction 2,567,208 1,954,834 Savings 8,214,059 6,625,177 Time 529,253 442,619 Total interest-bearing deposits 11,310,520 9,022,630 Total deposits $ 19,123,180 $ 17,016,831 The scheduled maturities of interest-bearing time deposits were as follows at December 31, 2017 (in thousands): 2018 $ 492,208 2019 33,289 2020 2,817 2021 246 2022 244 2023 and after 449 $ 529,253 At December 31, 2017 and 2016 , the Bank had approximately $13.5 million and $15.4 million, respectively, in deposits from related parties, including directors, stockholders and their affiliates. At December 31, 2017 and 2016 , interest-bearing time deposits of $250,000 or more were approximately $300.5 million and $225.5 million, respectively.

Borrowing Arrangements

Borrowing Arrangements	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Borrowing Arrangements	Borrowing Arrangements The following table summarizes our borrowings at December 31, 2017 , 2016 and 2015 (in thousands): December 31, 2017 2016 2015 Balance Rate(3) Balance Rate(3) Balance Rate(3) Federal funds purchased(4) $ 359,338 1.45 % $ 101,800 0.80 % $ 74,164 0.55 % Customer repurchase agreements(1) 5,702 0.03 % 7,775 0.05 % 68,887 0.02 % FHLB borrowings(2) 2,800,000 1.35 % 2,000,000 0.61 % 1,500,000 0.31 % Subordinated notes 281,406 5.86 % 281,044 5.87 % 280,682 5.75 % Trust preferred subordinated debentures 113,406 3.55 % 113,406 2.90 % 113,406 2.47 % Total borrowings $ 3,559,852 $ 2,504,025 $ 2,037,139 Maximum outstanding at any month end $ 3,559,852 $ 2,511,579 $ 2,042,457 (1) Securities pledged for customer repurchase agreements were $7.3 million , $10.2 million and $14.2 million at December 31, 2017 , 2016 and 2015 , respectively. (2) FHLB borrowings are collateralized by a blanket floating lien on certain real estate secured loans, mortgage finance assets and also certain pledged securities. The weighted-average interest rates of FHLB borrowings for the years ended December 31, 2017 , 2016 and 2015 were 1.08% , 0.43% and 0.18% , respectively. The average balance of FHLB borrowings for the years ended December 31, 2017 , 2016 and 2015 were $1.4 billion , $1.4 billion and $1.2 billion , respectively. (3) Interest rate as of period end. (4) The weighted-average interest rates on Federal funds purchased for the years ended December 31, 2017 , 2016 and 2015 were 1.20% , 0.57% and 0.29% , respectively. The average balances of Federal funds purchased for the years ended December 31, 2017 , 2016 and 2015 were $215.9 million , $90.9 million and $98.8 million , respectively. The following table summarizes our other borrowing capacities net of balances outstanding at December 31, 2017 , 2016 and 2015 (in thousands): December 31, 2017 2016 2015 FHLB borrowing capacity relating to loans $ 3,890,995 $ 3,057,915 $ 4,101,396 FHLB borrowing capacity relating to securities 2,071 1,653 1,213 Total FHLB borrowing capacity $ 3,893,066 $ 3,059,568 $ 4,102,609 Unused Federal funds lines available from commercial banks $ 885,000 $ 1,118,000 $ 1,231,000 Unused Federal Reserve Borrowings capacity $ 4,114,594 $ 3,179,087 $ 2,966,702 Our unsecured, revolving, non-amortizing line of credit has maximum availability of $130.0 million , matured on December 19, 2017 and was renewed on December 19, 2017 with a maturity date of December 18, 2018. The loan proceeds may be used for general corporate purposes including funding regulatory capital infusions into the Bank. The loan agreement contains customary financial covenants and restrictions. There were no borrowings outstanding as of December 31, 2017 or December 31, 2016 . We did not borrow against this line of credit during the year ended December 31, 2017 . The average borrowings during the year ended December 31, 2016 were $6.8 million . The scheduled maturities of our borrowings at December 31, 2017 , excluding accrued interest, were as follows (in thousands): Within One Year After One But Within Three Years After Three But Within Five Years After Five Years Total Federal funds purchased and customer repurchase agreements $ 365,040 $ — $ — $ — $ 365,040 FHLB borrowings 2,800,000 — — — 2,800,000 Subordinated notes — — — 281,406 281,406 Trust preferred subordinated debentures — — — 113,406 113,406 Total borrowings $ 3,165,040 $ — $ — $ 394,812 $ 3,559,852

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2017
Subordinated Borrowings [Abstract]
Long-Term Debt	Long-Term Debt From November 2002 to September 2006 various Texas Capital Statutory Trusts were created and subsequently issued floating rate trust preferred securities in various private offerings totaling $113.4 million . As of December 31, 2017 , the details of the trust preferred subordinated debentures are summarized below (dollars in thousands): Texas Capital Texas Capital Texas Capital Texas Capital Texas Capital Date issued November 19, 2002 April 10, 2003 October 6, 2005 April 28, 2006 September 29, 2006 Trust preferred securities issued $10,310 $10,310 $25,774 $25,774 $41,238 Floating or fixed rate securities Floating Floating Floating Floating Floating Interest rate on subordinated debentures 3 month LIBOR + 3.35% 3 month LIBOR + 3.25% 3 month LIBOR + 1.51% 3 month LIBOR + 1.60% 3 month LIBOR + 1.71% Maturity date November 2032 April 2033 December 2035 June 2036 December 2036 On September 21, 2012, we issued $111.0 million of subordinated notes. The notes mature in September 2042 and bear interest at a rate of 6.50% per annum, payable quarterly. The indenture governing the notes contains customary covenants and restrictions. On January 31, 2014, the Bank issued $175.0 million of subordinated notes in an offering to institutional investors exempt from registration under Section 3(a)(2) of the Securities Act of 1933 and 12 C.F.R. Part 16. The notes mature in January 2026 and bear interest at a rate of 5.25% per annum, payable semi-annually. The notes are unsecured and are subordinate to the Bank’s obligations to its depositors, its obligations under banker’s acceptances and letters of credit, certain obligations to Federal Reserve Banks and the FDIC and the Bank’s obligations to its other creditors, except any obligations which expressly rank on a parity with or junior to the notes. The notes qualify as Tier 2 capital for regulatory capital purposes, subject to applicable limitations. Interest payments on all long-term debt are deductible for federal income tax purposes.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Tax Cut and Jobs Act (the "Tax Act") enacted in December 2017 reduced the federal corporate income tax rate from 35% to 21% effective January 1, 2018. As a result of the Tax Act, we recorded a $17.6 million write-off of our net deferred tax asset, which was recorded as additional income tax expense during 2017. We reported gross deferred tax assets of $63.0 million and $89.7 million at December 31, 2017 and 2016 , respectively, which related primarily to our allowance for loan losses, loan origination fees and stock compensation. Management believes it is more likely than not that all of the deferred tax assets will be realized. Our net deferred tax assets are included in other assets in the consolidated balance sheets. Income tax expense/(benefit) consists of the following for the years ended (in thousands): Year ended December 31, 2017 2016 2015 Current: Federal $ 94,112 $ 86,612 $ 80,957 State 3,257 2,412 2,245 Total 97,369 89,024 83,202 Deferred Federal 31,276 (2,946 ) (3,561 ) State — — — Total 31,276 (2,946 ) (3,561 ) Total expense Federal 125,388 83,666 77,396 State 3,257 2,412 2,245 Total $ 128,645 $ 86,078 $ 79,641 The tax effect of unrealized gains and losses on available-for-sale securities is recorded to other comprehensive income and is not a component of income tax expense/(benefit). Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The table below summarizes significant components of our deferred tax assets and liabilities utilizing federal corporate income tax rates of 21% as of December 31, 2017 and 35% as of December 31, 2016 (in thousands): December 31, 2017 2016 Deferred tax assets: Allowance for credit losses $ 42,213 $ 64,009 Loan origination fees 10,084 13,536 Stock compensation 4,460 5,761 Non-accrual interest 1,680 2,537 Deferred lease expense 911 1,519 Other 3,686 2,322 Total deferred tax assets 63,034 89,684 Deferred tax liabilities: Loan origination costs (1,304 ) (1,722 ) Leases (6,850 ) (7,962 ) MSRs (17,619 ) (10,973 ) Depreciation (7,354 ) (6,941 ) Unrealized gain on securities (138 ) (223 ) Other (2,068 ) (2,971 ) Total deferred tax liabilities (35,333 ) (30,792 ) Net deferred tax asset $ 27,701 $ 58,892 We remeasured certain deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is generally 21%. However, we are still analyzing certain aspects of the Tax Act and refining our calculations, which could potentially affect the measurement of these balances or potentially give rise to new deferred tax amounts. The provisional amount recorded related to the remeasurement of our deferred tax asset was $17.6 million . ASC 740-10, Income Taxes — Accounting for Uncertainties in Income Taxes (“ASC 740-10”) prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. Benefits from tax positions should be recognized in the financial statements only when it is more likely than not that the tax position will be sustained upon examination by the appropriate taxing authority that would have full knowledge of all relevant information. A tax position that meets the more-likely-than-not recognition threshold is measured at the largest amount of cumulative benefit that is greater than fifty percent likely of being realized upon ultimate settlement. Tax positions that previously failed to meet the more-likely-than-not recognition threshold are recognized in the first subsequent financial reporting period in which that threshold is met. Previously recognized tax positions that no longer meet the more-likely-than-not recognition threshold are derecognized in the first subsequent financial reporting period in which that threshold is no longer met. ASC 740-10 also provides guidance on the accounting for and disclosure of unrecognized tax benefits, interest and penalties. We file income tax returns in the U.S. federal jurisdiction and several U.S. state jurisdictions. We are no longer subject to U.S. federal income tax examinations for years before 2014. The reconciliation of our effective income tax rate to the U.S. federal statutory tax rate is as follows: Year ended December 31, 2017 2016 2015 U.S. statutory rate 35 % 35 % 35 % State taxes 1 % 1 % 1 % Non-deductible expenses 1 % 1 % 1 % Deferred tax asset write-off 5 % — % — % Non-taxable income (1 )% (1 )% (1 )% Other (1 )% — % (1 )% Effective tax rate 40 % 36 % 35 %

Stock-Based Compensation and Em

Stock-Based Compensation and Employee Benefits	12 Months Ended
	Dec. 31, 2017
Compensation Related Costs [Abstract]
Stock-Based Compensation and Employee Benefits	Stock-Based Compensation and Employee Benefits We have a qualified retirement plan, with a salary deferral feature designed to qualify under Section 401 of the Internal Revenue Code (“the 401(k) Plan”). The 401(k) Plan permits our employees to defer a portion of their compensation. Matching contributions may be made in amounts and at times determined by the Company. We contributed approximately $8.4 million , $6.8 million , and $6.3 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. Employees are eligible to participate in the 401(k) Plan when they meet certain requirements concerning minimum age and period of credited service. All contributions to the 401(k) Plan are invested in accordance with participant elections among certain investment options. During 2000, we implemented an Employee Stock Purchase Plan (“ESPP”). Employees are eligible for the plan when they meet certain requirements concerning period of credited service and minimum hours worked. Eligible employees may contribute a minimum of 1% to a maximum of 10% of eligible compensation up to the Section 423 of the Internal Revenue Code limit of $25,000. In 2006, stockholders approved the 2006 ESPP, which allocated 400,000 shares for purchase. As of December 31, 2017 , 2016 and 2015 , 132,285 , 124,572 and 113,910 shares had been purchased on behalf of the employees under the 2006 ESPP. We have stock-based compensation plans under which equity-based compensation grants are made by the board of directors, or its designated committee. Grants are subject to vesting requirements. Under the plans, we may grant, among other things, non-qualified stock options, incentive stock options, restricted stock, restricted stock units (“RSUs”), stock appreciation rights (“SARs”), cash-based performance units or any combination thereof to employees and non-employee directors. A total of 2,550,000 shares are authorized for grant under the plans. Total shares remaining available for grant under the plans at December 31, 2017 were 2,169,324 . We also offer a non-qualified deferred compensation plan for our executives and key members of management in order to assist us in attracting and retaining these individuals. Participants in the plan may elect to defer up to 75% of their annual salary and/or short-term incentive payout into deferral accounts that mirror the gains or losses of investments selected by the participants. The plan allows us to make discretionary contributions on behalf of a participant as well as matching contributions. We made discretionary contributions of $260,000 in 2017 compared to no ne in 2016 . No matching contributions were made in 2017 or 2016. All participant contributions to the plan and any related earnings are immediately vested and may be withdrawn upon the participant's separation from service, death or disability or upon a date specified by the participant. The deferrals are recorded to salaries and benefits as a reduction and a corresponding accrual is recorded in other liabilities. A summary of our SAR activity and related information for 2017 , 2016 and 2015 is as follows. These rights are time based and generally vest ratably over a period of five years. December 31, 2017 December 31, 2016 December 31, 2015 SARs Weighted Average Exercise Price SARs Weighted SARs Weighted SARs outstanding at beginning of year 125,863 $ 31.68 360,544 $ 25.73 445,009 $ 24.83 SARs granted — — — — — — SARs exercised (51,500 ) 33.94 (234,681 ) 22.54 (84,465 ) 20.97 SARs forfeited — — — — — — SARs outstanding at year-end 74,363 $ 30.12 125,863 $ 31.68 360,544 $ 25.73 SARs vested and exercisable at year-end 60,463 $ 26.02 94,463 $ 26.73 307,144 $ 22.49 Weighted average remaining contractual life of SARs vested 2.82 3.62 2.36 Compensation expense $ 265,000 $ 307,000 $ 367,000 Unrecognized compensation expense $ 127,000 $ 392,000 $ 699,000 Weighted average period over which unrecognized compensation expense is expected to be recognized (in years) 0.75 1.52 2.40 Fair value of shares vested during the year $ 294,000 $ 337,000 $ 436,000 Weighted average remaining contractual life of SARs currently outstanding (in years) 3.35 4.32 3.08 Intrinsic value of SARs exercised $ 3,802,000 $ 4,881,000 $ 8,291,000 A summary of our RSU activity and related information for 2017 , 2016 and 2015 is as follows. Grants of RSUs include both performance-based and time-based vesting conditions and generally vest over a three-year period. December 31, 2017 December 31, 2016 December 31, 2015 RSUs Weighted Average Grant Date Fair Value RSUs Weighted RSUs Weighted RSUs outstanding at beginning of year 425,055 $ 51.28 333,174 $ 48.60 295,165 $ 42.93 RSUs granted 121,243 80.40 213,577 51.75 145,952 51.96 RSUs exercised (102,057 ) 48.93 (94,296 ) 42.87 (95,743 ) 38.05 RSUs forfeited (20,509 ) 54.75 (27,400 ) 51.18 (12,200 ) 43.89 RSUs outstanding at year-end 423,732 $ 60.01 425,055 $ 51.28 333,174 $ 48.60 Compensation expense $ 7,790,000 $ 4,771,000 $ 4,230,000 Unrecognized compensation expense $ 18,730,000 $ 17,167,000 $ 13,038,000 Weighted average period over which unrecognized compensation expense is expected to be recognized (in years) 3.15 3.37 3.30 Weighted average remaining contractual life of RSUs currently outstanding 8.33 8.65 8.29 In 2016 , we began granting shares of restricted stock ("RSAs"). A summary of our restricted stock activity and related information for 2017 and 2016 is as follows. These restricted shares are time-vested and generally vest ratably over a period of five years. December 31, 2017 December 31, 2016 Number of Shares Weighted Number of Shares Weighted RSAs with restrictions outstanding at beginning of year 1,472 $ 33.97 — $ — RSAs granted 641 78.00 1,472 33.97 RSAs lapsed restrictions (491 ) 33.97 — — RSAs with restrictions outstanding at year-end 1,622 $ 51.37 1,472 $ 33.97 Compensation expense $ 24,000 $ 15,000 Unrecognized compensation expense $ 61,000 $ 35,000 Weighted average period over which unrecognized compensation expense is expected to recognized (in years) 2.10 2.10 Weighted average remaining contractual life of RSUs currently outstanding 8.69 9.13 Total compensation cost for all share-based arrangements, net of taxes, was $5.3 million, $3.3 million and $3.0 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. We granted a total of 121,260 cash-based performance units in 2017 , with a total of 390,350 outstanding at December 31, 2017 all of which are time-based and vest ratably over a period of four years . We granted a total of 224,071 and 146,153 cash-based performance units in 2016 and 2015 . Since these units have a cash payout feature, they are accounted for under the liability method and the related expense is based on the stock price at period end. Compensation cost for the units was $13.9 million, $8.5 million and $7.7 million for the years ended December 31, 2017 , 2016 and 2015 respectively. At December 31, 2017 , the weighted average remaining contractual life of the units was 7.97 years. Total compensation cost for all cash-based arrangements, net of taxes, for the years ended December 31, 2017 , 2016 and 2015 was $9.1 million, $5.5 million and $5.0 million, respectively.

Financial Instruments with Off-

Financial Instruments with Off-Balance Sheet Risk	12 Months Ended
	Dec. 31, 2017
Risks and Uncertainties [Abstract]
Financial Instruments with Off-Balance Sheet Risk	Financial Instruments with Off-Balance Sheet Risk The Bank is a party to financial instruments with off-balance sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include commitments to extend credit and standby letters of credit that involve varying degrees of credit risk in excess of the amount recognized in the consolidated balance sheets. The Bank’s exposure to credit loss in the event of non-performance by the other party to the financial instrument for commitments to extend credit and standby letters of credit is represented by the contractual amount of these instruments. The Bank uses the same credit policies in making commitments and conditional obligations as it does for on-balance sheet instruments. The amount of collateral obtained, if deemed necessary, is based on management’s credit evaluation of the borrower. Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many of the commitments may expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Bank evaluates each customer’s credit-worthiness on a case-by-case basis. Standby letters of credit are conditional commitments issued by the Bank to guarantee the performance of a customer to a third party. Those guarantees are primarily issued to support public and private borrowing arrangements. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. At December 31, 2017 and 2016 , commitments to extend credit and standby and commercial letters of credit were as follows (in thousands): December 31, 2017 2016 Commitments to extend credit $ 6,957,847 $ 5,704,381 Standby letters of credit 230,958 171,266 At December 31, 2017 and 2016 , we had $9.1 million and $11.4 million , respectively, in allowance for off-balance sheet credit losses related to these off-balance sheet commitments recorded in other liabilities in the consolidated balance sheets.

Regulatory Restrictions

Regulatory Restrictions	12 Months Ended
	Dec. 31, 2017
Regulatory Capital Requirements [Abstract]
Regulatory Restrictions	Regulatory Restrictions The Company and the Bank are subject to various regulatory capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory (and possibly additional discretionary) actions by regulators that, if undertaken, could have a direct material effect on the Company’s and the Bank’s financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Company and the Bank must meet specific capital guidelines that involve quantitative measures of the Company’s and the Bank’s assets, liabilities, and certain off-balance sheet items as calculated under regulatory accounting practices. The Company’s and the Bank’s capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings and other factors. The Basel III regulatory capital framework (the "Basel III Capital Rules") adopted by U.S. federal regulatory authorities, among other things, (i) establishes the capital measure called "Common Equity Tier 1" ("CET1"), (ii) specifies that Tier 1 capital consist of CET1 and "Additional Tier 1 Capital" instruments meeting stated requirements, (iii) requires that most deductions/adjustments to regulatory capital measures be made to CET1 and not to the other components of capital and (iv) defines the scope of the deductions/adjustments to the capital measures. The Basel III Capital Rules became effective for us on January 1, 2015 with certain transition provisions fully phasing in over a period ending on January 1, 2019. Additionally, the Basel III Capital Rules require that we maintain a capital conservation buffer with respect to each of the CET1, Tier 1 and total capital to risk-weighted assets, which provides for capital levels that exceed the minimum risk-based capital adequacy requirements. The capital conservation buffer is subject to a three year phase-in period that began on January 1, 2016 and will be fully phased-in on January 1, 2019 at 2.5%. The required phase-in capital conservation buffer during 2017 was 1.25%. A financial institution with a conservation buffer of less than the required amount is subject to limitations on capital distributions, including dividend payments and stock repurchases, and certain discretionary bonus payments to executive officers. Quantitative measures established by regulation to ensure capital adequacy require the Company and the Bank to maintain minimum amounts and ratios of CET1, Tier 1 and total capital to risk-weighted assets, and of Tier 1 capital to average assets, each as defined in the regulations. Management believes, as of December 31, 2017 , that the Company and the Bank meet all capital adequacy requirements to which they are subject. Financial institutions are categorized as well capitalized or adequately capitalized, based on minimum total risk-based, Tier 1 risk-based, CET1 and Tier 1 leverage ratios. As shown in the table below, the Company’s capital ratios exceeded the regulatory definition of adequately capitalized as of December 31, 2017 and 2016 . Based upon the information in its most recently filed call report, the Bank met the capital ratios necessary to be well capitalized. The regulatory authorities can apply changes in classification of assets and such changes may retroactively subject the Company to changes in capital ratios. Any such change could reduce one or more capital ratios below well-capitalized status. In addition, a change may result in imposition of additional assessments by the FDIC or could result in regulatory actions that could have a material effect on condition and results of operations. Because our Bank had less than $15.0 billion in total consolidated assets as of December 31, 2009, we are allowed to continue to classify our trust preferred securities, all of which were issued prior to May 19, 2010, as Tier 1 capital. The table below summarizes our actual and required capital ratios under the Basel III Capital Rules (dollars in thousands): Actual Minimum Capital Required - Basel III Phase-In Schedule Minimum capital Required - Basel III Fully Phased-In Required to be Considered Well Capitalized Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio As of December 31, 2017: CET1 Company $ 2,033,830 8.45 % $ 1,384,448 5.75 % $ 1,685,464 7.00 % N/A N/A Bank 1,992,152 8.28 % 1,383.475 5.75 % 1,684.231 7.00 % 1,563,929 6.50 % Total capital (to risk-weighted assets) Company 2,768,153 11.50 % 2,227.221 9.250 % 2,528.196 10.50 % N/A N/A Bank 2,567,961 10.67 % 2,225.591 9.250 % 2,526.347 10.50 % 2,406,044 10.00 % Tier 1 capital (to risk-weighted assets) Company 2,293,016 9.52 % 1,745.659 7.25 % 2,046.635 8.50 % N/A N/A Bank 2,151,338 8.94 % 1,744.382 7.25 % 2,045.138 8.50 % 1,924,835 8.00 % Tier 1 capital (to average assets)(1) Company 2,293,016 9.15 % 1,002,494 4.00 % 1,002,494 4.00 % N/A N/A Bank 2,151,338 8.59 % 1,002,144 4.00 % 1,002,144 4.00 % 1,252,680 5.00 % As of December 31, 2016: CET1 Company $ 1,841,219 8.97 % $ 1,052,205 5.125 % $ 1,437,159 7.00 % N/A N/A Bank 1,735,496 8.45 % 1,051.989 5.125 % 1,436.863 7.00 % 1,334,244 6.50 % Total capital (to risk-weighted assets) Company 2,561,663 12.48 % 1,770.766 8.625 % 2,155.715 10.50 % N/A N/A Bank 2,297,528 11.19 % 1,770.421 8.625 % 2,155.295 10.50 % 2,052,683 10.00 % Tier 1 capital (to risk-weighted assets) Company 2,101,071 10.23 % 1,360.154 6.625 % 1,745.103 8.50 % N/A N/A Bank 1,895,348 9.23 % 1,359.888 6.625 % 1,744.762 8.50 % 1,642,147 8.00 % Tier 1 capital (to average assets)(1) Company 2,101,071 9.34 % 900,268 4.00 % 900,268 4.00 % N/A N/A Bank 1,895,348 8.42 % 900,070 4.00 % 900,070 4.00 % 1,125,087 5.00 % (1) The Tier 1 capital ratio (to average assets) is not impacted by the Basel III Capital Rules; however, it should be noted that the Federal Reserve Board and the FDIC may require the Company and the Bank, respectively, to maintain a Tier 1 capital ratio (to average assets) above the required minimum. Our mortgage finance loan volumes can increase significantly at month-end, causing a meaningful difference between ending balance and average balance for any period. At December 31, 2017 , our total mortgage finance loans were $5.3 billion compared to the average for the year ended December 31, 2017 of $4.1 billion . As CET1, Tier 1 and total capital ratios are calculated using quarter-end risk-weighted assets and our mortgage finance loans are 100% risk-weighted (excluding MCA mortgage loans held for sale, which receive lower risk weights), the quarter-end fluctuation in these balances can significantly impact our reported ratios. Due to the actual risk profile and liquidity of this asset class, we manage capital allocated to mortgage finance loans based on changing trends in average balances and do not believe that the quarter-end balance is representative of risk characteristics that would justify higher allocations. However, we monitor our capital allocation to confirm that all capital levels remain above well-capitalized levels. Dividends that may be paid by banks are routinely restricted by various regulatory authorities. The amount that can be paid in any calendar year without prior approval of our Bank’s regulatory agencies cannot exceed the lesser of the net profits (as defined) for that year plus the net profits for the preceding two calendar years, or retained earnings. The Basel III Capital Rules further limit the amount of dividends that may be paid by our Bank. No dividends were declared or paid on our common stock during 2017 , 2016 or 2015 . The required reserve balances at the Federal Reserve at December 31, 2017 and 2016 were approximately $197.3 million and $221.9 million, respectively.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The following table presents the computation of basic and diluted earnings per share (in thousands except share data): Year ended December 31, 2017 2016 2015 Numerator: Net income $ 197,063 $ 155,119 $ 144,854 Preferred stock dividends 9,750 9,750 9,750 Net income available to common stockholders $ 187,313 $ 145,369 $ 135,104 Denominator: Denominator for basic earnings per share—weighted average shares 49,587,169 46,239,210 45,808,440 Effect of employee stock-based awards(1) 239,008 128,228 211,168 Effect of warrants to purchase common stock 433,657 398,464 418,264 Denominator for dilutive earnings per share—adjusted weighted average shares and assumed conversions 50,259,834 46,765,902 46,437,872 Basic earnings per common share $ 3.78 $ 3.14 $ 2.95 Diluted earnings per common share $ 3.73 $ 3.11 $ 2.91 (1) SARs and RSUs outstanding of 13,500 , 150,416 and 64,700 in 2017 , 2016 and 2015 , respectively, have not been included in diluted earnings per share because to do so would have been antidilutive for the periods presented.

Fair Value Disclosures

Fair Value Disclosures	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Disclosures	Fair Value Disclosures We determine the fair market values of our assets and liabilities measured at fair value on a recurring and nonrecurring basis using the fair value hierarchy as prescribed in ASC 820, Fair Value Measurements and Disclosures . The standard describes three levels of inputs that may be used to measure fair value as provided below. Level 1 Quoted prices in active markets for identical assets or liabilities. This category includes the assets and liabilities related to our non-qualified deferred compensation plan where values are based on quoted market prices for identical equity securities in an active market. Level 2 Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 2 assets include U.S. government and agency mortgage-backed debt securities, municipal bonds, and Community Reinvestment Act funds. This category also includes loans held for sale and derivative assets and liabilities where values are obtained from independent pricing services using 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. Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair values requires significant management judgment or estimation. This category includes impaired loans and OREO where collateral values have been based on third party appraisals; however, due to current economic conditions, comparative sales data typically used in appraisals may be unavailable or more subjective due to lack of market activity. Assets and liabilities measured at fair value at December 31, 2017 and 2016 are as follows (in thousands): Fair Value Measurements Using December 31, 2017 Level 1 Level 2 Level 3 Available for sale securities:(1) Residential mortgage-backed securities $ — $ 10,945 $ — Municipals — — — Equity securities(2) 5,460 7,106 — Loans held for sale(3) — 1,007,695 — Loans held for investment(4)(6) — — 21,216 OREO(5)(6) — — 11,742 Derivative assets(7) — 16,719 — Derivative liabilities(7) — 17,377 — Non-qualified deferred compensation plan liabilities(8) 5,587 — — December 31, 2016 Available for sale securities:(1) Residential mortgage-backed securities $ — $ 15,652 $ — Municipals — 275 — Equity securities(2) 1,786 7,161 — Loans held for sale(3) — 968,929 — Loans held for investment(4)(6) — — 52,323 OREO(5)(6) — — 18,961 Derivative assets(7) — 37,878 — Derivative liabilities(7) — 26,240 — Non-qualified deferred compensation plan liabilities(8) 1,811 — — (1) Securities are measured at fair value on a recurring basis, generally monthly. (2) Equity securities consist of Community Reinvestment Act funds and investments related to our non-qualified deferred compensation plan. (3) Loans held for sale, excluding SBA loans which are carried at lower of cost or market, are measured at fair value on a recurring basis, generally monthly. (4) Includes impaired loans that have been measured for impairment at the fair value of the loan’s collateral. (5) OREO is transferred from loans to OREO at fair value less selling costs. (6) Loans held for investment and OREO are measured on a nonrecurring basis, generally annually or more often as warranted by market and economic conditions (7) Derivative assets and liabilities are measured at fair value on a recurring basis, generally quarterly. (8) Non-qualified deferred compensation plan liabilities represent the fair value of the obligation to the employee, which corresponds to the fair value of the invested assets, and are measured at fair value on a recurring basis, generally monthly. Level 3 Valuations Financial instruments are considered Level 3 when their values are determined using pricing models, discounted cash flow methodologies or similar techniques and at least one significant model assumption or input is unobservable. Level 3 financial instruments also include those for which the determination of fair value requires significant management judgment or estimation. Currently, we measure fair value for certain loans and OREO on a nonrecurring basis as described below. Loans held for investment During the years ended December 31, 2017 and 2016 , certain impaired loans held for investment were re-evaluated and reported at fair value through a specific valuation allowance allocation of the allowance for loan losses based upon the fair value of the underlying collateral. The $21.2 million total above includes impaired loans at December 31, 2017 with a carrying value of $32.2 million that were reduced by specific valuation allowance allocations totaling $11.0 million for a total reported fair value of $21.2 million based on collateral valuations utilizing Level 3 valuation inputs. The $52.3 million total above includes impaired loans at December 31, 2016 with a carrying value of $74.1 million that were reduced by specific valuation allowance allocations totaling $21.8 million for a total reported fair value of $52.3 million based on collateral valuations utilizing Level 3 valuation inputs. Fair values were based on third party appraisals. OREO Certain foreclosed assets, upon initial recognition, are recorded at fair value less estimated selling costs. At December 31, 2017 and 2016 , OREO had a carrying value of $11.7 million and $19.0 million , respectively, with no specific valuation allowance. The fair value of OREO was computed based on third party appraisals, which are Level 3 valuation inputs. Fair Value of Financial Instruments Generally accepted accounting principles require disclosure of fair value information about financial instruments, whether or not recognized on the balance sheet, for which it is practical to estimate that value. In cases where quoted market prices are not available, fair values are based on estimates using present value or other valuation techniques. Those techniques are significantly affected by the assumptions used, including the discount rate and estimates of future cash flows. This disclosure does not and is not intended to represent the fair value of the Company. A summary of the carrying amounts and estimated fair values of financial instruments is as follows (in thousands): December 31, 2017 December 31, 2016 Carrying Amount Estimated Fair Value Carrying Estimated Financial assets: Level 1 inputs: Cash and cash equivalents $ 2,905,591 $ 2,905,591 $ 2,839,352 $ 2,839,352 Securities, available-for-sale 5,460 5,460 1,786 1,786 Level 2 inputs: Securities, available-for-sale 18,051 18,051 23,088 23,088 Loans held for sale 1,011,004 1,011,004 968,929 968,929 Derivative assets 16,719 16,719 37,878 37,878 Level 3 inputs: Loans held for investment, net 20,489,757 20,480,802 17,330,223 17,347,199 Financial liabilities: Level 2 inputs: Federal funds purchased 359,338 359,338 101,800 101,800 Customer repurchase agreements 5,702 5,702 7,775 7,775 Other borrowings 2,800,000 2,800,000 2,000,000 2,000,000 Subordinated notes 281,406 322,415 281,044 304,672 Derivative liabilities 17,377 17,377 26,240 26,240 Level 3 inputs: Deposits 19,123,180 19,124,121 17,016,831 17,017,221 Trust preferred subordinated debentures 113,406 113,406 113,406 113,406 The following methods and assumptions were used by the Company in estimating its fair value disclosures for financial instruments: Cash and cash equivalents The carrying amounts reported in the consolidated balance sheets for cash and cash equivalents approximate their fair value, and these financial instruments are characterized as Level 1 assets in the fair value hierarchy. Securities available-for-sale Within the securities available-for-sale portfolio, we hold equity securities related to our non-qualified deferred compensation plan which are valued using quoted market prices for identical equity securities in an active market. These financial instruments are classified as Level 1 assets in the fair value hierarchy. The fair value of the remaining investment portfolio is based on prices obtained from independent pricing services which are based on quoted market prices for the same or similar securities, and these financial instruments are characterized as Level 2 assets in the fair value hierarchy. We have obtained documentation from the primary pricing service we use about their processes and controls over pricing. In addition, on a quarterly basis we independently verify the prices that we receive from the service provider using two additional independent pricing sources. Any significant differences are investigated and resolved. Loans held for sale Fair value for loans held for sale is derived from quoted market prices for similar loans, and these financial instruments are characterized as Level 2 assets in the fair value hierarchy. Loans held for investment, net Loans held for investment are characterized as Level 3 assets in the fair value hierarchy. For variable-rate loans held for investment that reprice frequently with no significant change in credit risk, fair values are generally based on carrying values. The fair value for all other loans held for investment is estimated using discounted cash flow analyses, using interest rates currently being offered for loans with similar terms to borrowers of similar credit quality. The carrying amount of accrued interest approximates its fair value. Derivatives The estimated fair value of the interest rate swaps and caps is obtained from independent pricing services based on quoted market prices for similar derivative contracts and these financial instruments are characterized as Level 2 assets and liabilities in the fair value hierarchy. On a quarterly basis, we independently verify the fair value using an additional independent pricing source. Any significant differences are investigated and resolved. Foreign currency forward contracts are valued based upon quoted market prices obtained from independent pricing services for similar derivative contracts. As such, these financial instruments are characterized as Level 2 assets and liabilities in the fair value hierarchy. The derivative instruments related to the loans held for sale portfolio include loan purchase commitments and forward sales commitments. Loan purchase commitments are valued based upon the fair value of the underlying mortgage loans to be purchased, which is based on observable market data for similar loans. Forward sales commitments are valued based upon the quoted market prices from brokers. As such, these loan purchase commitments and forward sales commitments are classified as Level 2 assets or liabilities in the fair value hierarchy. Deposits Deposits are characterized as Level 3 liabilities in the fair value hierarchy. The carrying amounts for variable-rate money market accounts approximate their fair value. The fair value of fixed-term certificates of deposit are estimated using a discounted cash flow calculation that applies interest rates currently being offered on certificates to a schedule of aggregated expected monthly maturities. Federal funds purchased, customer repurchase agreements, other borrowings, subordinated notes and trust preferred subordinated debentures The carrying value reported in the consolidated balance sheets for Federal funds purchased, customer repurchase agreements and other short-term, floating rate borrowings approximates their fair value, and these financial instruments are characterized as Level 2 liabilities in the fair value hierarchy. The fair value of any fixed rate short-term borrowings and trust preferred subordinated debentures are estimated using a discounted cash flow calculation that applies interest rates currently being offered on similar borrowings, and these financial instruments are characterized as Level 3 liabilities in the fair value hierarchy. The subordinated notes are publicly, though infrequently, traded and are valued based on market prices, and are characterized as Level 2 liabilities in the fair value hierarchy.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies We lease various premises under operating leases with various expiration dates extending through April 2027. Rent expense incurred under operating leases totaled approximately $15.3 million, $13.9 million and $15.3 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. Minimum future lease payments under operating leases are as follows (in thousands): Year ending December 31, Minimum Payments 2018 $ 16,446 2019 16,137 2020 15,286 2021 12,805 2022 12,138 2023 and thereafter 17,299 $ 90,111

Parent Company Only

Parent Company Only	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Parent Company Only	Parent Company Only Summarized financial information for Texas Capital Bancshares, Inc. – Parent Company Only follows (in thousands): Balance Sheet December 31, 2017 2016 Assets Cash and cash equivalents $ 144,635 $ 220,499 Loans held for investment (net of unearned income) 7,500 — Investment in subsidiaries 2,184,601 1,927,392 Other assets 86,300 85,560 Total assets $ 2,423,036 $ 2,233,451 Liabilities and Stockholders’ Equity Other liabilities $ 1,244 $ 1,284 Subordinated notes 108,513 108,412 Trust preferred subordinated debentures 113,406 113,406 Total liabilities 223,163 223,102 Preferred stock 150,000 150,000 Common stock 496 495 Additional paid-in capital 971,457 965,620 Retained earnings 1,077,500 893,827 Treasury stock (8 ) (8 ) Accumulated other comprehensive income 428 415 Total stockholders’ equity 2,199,873 2,010,349 Total liabilities and stockholders’ equity $ 2,423,036 $ 2,233,451 Statement of Earnings Year ended December 31, 2017 2016 2015 Interest on loans $ 3,271 $ 3,250 $ 3,250 Dividend income 10,400 10,400 10,400 Other income 108 90 76 Total income 13,779 13,740 13,726 Other non-interest income 13 152 8 Interest expense 10,908 10,525 9,867 Salaries and employee benefits 489 431 499 Legal and professional 1,700 1,429 1,640 Other non-interest expense 1,761 1,594 1,637 Total expense 14,858 13,979 13,643 Income (loss) before income taxes and equity in undistributed income of subsidiary (1,066 ) (87 ) 91 Income tax expense (benefit) (371 ) (33 ) 33 Income (loss) before equity in undistributed income of subsidiary (695 ) (54 ) 58 Equity in undistributed income of subsidiary 194,118 151,445 141,041 Net income 193,423 151,391 141,099 Preferred stock dividends 9,750 9,750 9,750 Net income available to common stockholders $ 183,673 $ 141,641 $ 131,349 Statements of Cash Flows Year ended December 31, 2017 2016 2015 (in thousands) Operating Activities Net income $ 193,423 $ 151,391 $ 141,099 Adjustments to reconcile net income to net cash used in operating activities: Equity in undistributed income of subsidiary (194,118 ) (151,445 ) (141,041 ) Amortization 101 101 100 Increase in other assets (739 ) (10 ) (2,223 ) Excess tax benefits from stock-based compensation arrangements — (2,013 ) (1,499 ) Increase in other liabilities (40 ) 165 (209 ) Net cash used in operating activities of continuing operations (1,373 ) (1,811 ) (3,773 ) Investing Activities Net increase in loans held for investment (7,500 ) — — Investments in and advances to subsidiaries (55,000 ) (57,000 ) (110,000 ) Net cash used in investing activities (62,500 ) (57,000 ) (110,000 ) Financing Activities Proceeds from sale of stock related to stock-based awards (2,241 ) (2,481 ) (1,239 ) Proceeds from sale of common stock — 236,467 — Preferred dividends paid (9,750 ) (9,750 ) (9,750 ) Net other borrowings — — — Excess tax benefits from stock-based compensation arrangements — 2,013 1,499 Net cash provided by (used in) financing activities (11,991 ) 226,249 (9,490 ) Net increase (decrease) in cash and cash equivalents (75,864 ) 167,438 (123,263 ) Cash and cash equivalents at beginning of year 220,499 53,061 176,324 Cash and cash equivalents at end of year $ 144,635 $ 220,499 $ 53,061

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions See Note 8 for a description of deposits from related parties.

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments The fair value of derivative positions outstanding is included in accrued interest receivable and other assets and other liabilities in the accompanying consolidated balance sheets on a net basis when a right of offset exists, based on transactions with a single counterparty that are subject to a legally enforceable master netting agreement. We enter into interest rate derivative contracts that are not designated as hedging instruments. These derivative positions relate to transactions in which we enter into an interest rate swap, cap and/or floor with a customer while at the same time entering into an offsetting interest rate swap, cap and/or floor with another financial institution. In connection with each swap transaction, we agree to pay interest to the customer on a notional amount at a variable interest rate and receive interest from the customer on a similar notional amount at a fixed interest rate. At the same time, we agree to pay another financial institution the same fixed interest rate on the same notional amount and receive the same variable interest rate on the same notional amount. The transaction allows our customer to effectively convert a variable rate loan to a fixed rate. Because we act as an intermediary for our customer, changes in the fair value of the underlying derivative contracts substantially offset each other and do not have a material impact on our results of operations. We also enter into foreign currency forward contracts that are not designed as hedging instruments. These derivative instruments relate to transactions in which we enter into a contract with a customer to buy or sell a foreign currency at a future date for a specified price while at the same time entering into an offsetting contract with a financial institution to buy or sell the same currency at the same future date for a specified price. These transactions allow our customers to manage their exposure to foreign currency exchange rate fluctuations. We also enter into loan purchase commitment contracts with mortgage originators to purchase residential mortgage loans at a future date, as well as forward sales commitment contracts to sell residential mortgage loans at a future date as part of our MCA program. The objective of these transactions is to mitigate our exposure to interest rate risk associated with the purchase of mortgage loans held for sale. The notional amounts and estimated fair values of derivative positions outstanding at December 31, 2017 and 2016 are presented in the following table (in thousands): December 31, 2017 December 31, 2016 Estimated Fair Value Estimated Fair Value Notional Amount Asset Derivative Liability Derivative Notional Amount Asset Derivative Liability Derivative Non-hedging derivatives: Financial institution counterparties: Commercial loan/lease interest rate swaps $ 1,393,764 $ 4,736 $ 15,482 $ 1,144,367 $ 1,754 $ 25,421 Commercial loan/lease interest rate caps 242,700 421 7 210,996 819 — Foreign currency forward contracts 2,466 4 69 — — — Customer counterparties: Commercial loan/lease interest rate swaps 1,393,764 15,482 4,736 1,144,367 25,421 1,754 Commercial loan/lease interest rate caps 242,700 7 421 210,996 — 819 Foreign currency forward contracts 2,466 69 4 — — — Economic hedging interest rate derivatives: Loan purchase commitments 253,815 635 190 237,805 1,351 — Forward sale commitments 1,086,224 — 1,103 1,218,000 10,287 — Gross derivatives 21,354 22,012 39,632 27,994 Offsetting derivative assets/liabilities (4,635 ) (4,635 ) (1,754 ) (1,754 ) Net derivatives included in the consolidated balance sheets $ 16,719 $ 17,377 $ 37,878 $ 26,240 The weighted-average receive and pay interest rates for interest rate swaps outstanding at December 31, 2017 and 2016 were as follows: December 31, 2017 Weighted-Average Interest Rate December 31, 2016 Received Paid Received Paid Non-hedging interest rate swaps 3.59 % 4.34 % 3.17 % 4.58 % The weighted-average strike rate for outstanding interest rate caps was 2.40% at December 31, 2017 and 2.45% at December 31, 2016 . Our credit exposure on derivative instruments is limited to the net favorable value and interest payments by each counterparty. In such cases collateral may be required from the counterparties involved if the net value of the derivative instruments exceed a nominal amount considered to be immaterial. Our credit exposure associated with these instruments was approximately $16.7 million at December 31, 2017 and approximately $37.9 million at December 31, 2016 , which primarily relates to transactions with Bank customers. Collateral levels are monitored and adjusted on a regular basis for changes in interest rate swap and cap values, as well as forward sales commitments. At December 31, 2017 , we had $15.2 million in cash collateral pledged for these derivatives, of which $14.0 million was included in interest-bearing deposits and $1.2 million was included in accrued interest receivable and other assets. At December 31, 2016 , we had $24.8 million in cash collateral pledged for these derivatives, all of which was included in interest-bearing deposits. We also enter into credit risk participation agreements with financial institution counterparties for interest rate swaps related to loans in which we are either a participant or a lead bank. The risk participation agreements entered into by us as a participant bank provide credit protection to the financial institution counterparty should the borrower fail to perform on its interest rate derivative contract with that financial institution. We have 15 risk participation agreements where we are a participant bank with a notional amount of $157.1 million at December 31, 2017 . The maximum estimated exposure to these agreements, assuming 100% default by all obligors, was approximately $221,000 at December 31, 2017 . The fair value of these exposures was insignificant to the consolidated financial statements. Risk participation agreements entered into by us as the lead bank provide credit protection to us should the borrower fail to perform on its interest rate derivative contract with us. We have 10 risk participation agreements where we are the lead bank with a notional amount of $86.3 million at December 31, 2017 .

Stockholder's Equity

Stockholder's Equity	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity On December 2, 2016, we completed a sale of 3.45 million shares of our common stock in a public offering. Net proceeds from the sale totaled $236.4 million . The additional equity was used for general corporate purposes, including repayment of $20.0 million of short-term debt and as additional capital to support continued loan growth.

Quarterly Financial Data

Quarterly Financial Data	12 Months Ended
	Dec. 31, 2017
Selected Quarterly Financial Information [Abstract]
Quarterly Financial Information	Quarterly Financial Data (unaudited) The tables below summarize our quarterly financial information for the years December 31, 2017 and 2016 (in thousands except per share and average share data): 2017 Selected Quarterly Financial Data Fourth Third Second First Interest income $ 249,519 $ 237,643 $ 208,191 $ 183,946 Interest expense 38,870 33,282 25,232 20,587 Net interest income 210,649 204,361 182,959 163,359 Provision for credit losses 2,000 20,000 13,000 9,000 Net interest income after provision for credit losses 208,649 184,361 169,959 154,359 Non-interest income 19,374 19,003 18,769 17,110 Non-interest expense 133,138 114,830 111,814 106,094 Income before income taxes 94,885 88,534 76,914 65,375 Income tax expense 50,143 29,850 25,819 22,833 Net income 44,742 58,684 51,095 42,542 Preferred stock dividends 2,437 2,438 2,437 2,438 Net income available to common stockholders $ 42,305 $ 56,246 $ 48,658 $ 40,104 Basic earnings per share: $ 0.85 $ 1.13 $ 0.98 $ 0.81 Diluted earnings per share: $ 0.84 $ 1.12 $ 0.97 $ 0.80 Average shares Basic 49,630,000 49,607,000 49,577,000 49,536,000 Diluted 50,312,000 50,251,000 50,230,000 50,234,000 2016 Selected Quarterly Financial Data Fourth Third Second First Interest income $ 188,671 $ 182,492 $ 172,442 $ 159,803 Interest expense 17,448 15,753 15,373 15,020 Net interest income 171,223 166,739 157,069 144,783 Provision for credit losses 9,000 22,000 16,000 30,000 Net interest income after provision for credit losses 162,223 144,739 141,069 114,783 Non-interest income 18,835 16,716 13,932 11,297 Non-interest expense 106,523 94,799 94,255 86,820 Income before income taxes 74,535 66,656 60,746 39,260 Income tax expense 26,149 23,931 21,866 14,132 Net income 48,386 42,725 38,880 25,128 Preferred stock dividends 2,437 2,438 2,437 2,438 Net income available to common stockholders $ 45,949 $ 40,287 $ 36,443 $ 22,690 Basic earnings per share: $ 0.97 $ 0.88 $ 0.79 $ 0.49 Diluted earnings per share: $ 0.96 $ 0.87 $ 0.78 $ 0.49 Average shares Basic 47,156,000 45,981,000 45,924,000 45,889,000 Diluted 47,760,000 46,510,000 46,438,000 46,354,000

New Accounting Standards

New Accounting Standards	12 Months Ended
	Dec. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Standards	New Accounting Standards ASU 2017-12, “Derivatives and Hedging (Topic 815) - Targeted Improvements to Accounting for Hedging Activities” ("ASU 2017-12") amends the hedge accounting recognition and presentation requirements in ASC 815 to improve the transparency and understandability of information conveyed to financial statement users about an entity’s risk management activities to better align the entity’s financial reporting for hedging relationships with those risk management activities and to reduce the complexity of and simplify the application of hedge accounting. ASU 2017-12 will be effective for us on January 1, 2019 and is not expected to have a significant impact on our consolidated financial statements. ASU 2017-09 "Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting" ("ASU 2017-09") clarifies when changes to the terms or conditions of a share-based payment must be accounted for as modifications. Under ASU 2017-09, an entity should account for changes to the terms or conditions of a share-based payment as a modification unless all of the following are met: 1) the fair value of the modified award is the same as the fair value of the original award immediately before modification, 2) the vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before modification and 3) the classification of the modified award as an equity instrument or a liability instrument is the same as the classification of the original award immediately before modification. ASU 2017-09 will be effective for us on January 1, 2018, and is not expected to have a significant impact on our consolidated financial statements. ASU 2017-04, “Intangibles - Goodwill and Other (Topic 350) - Simplifying the Test for Goodwill Impairment” ("ASU 2017-04") eliminates Step 2 from the goodwill impairment test which required entities to compute the implied fair value of goodwill. Under ASU 2017-04, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. ASU 2017-04 will be effective for us on January 1, 2020, with early adoption permitted for interim or annual impairment tests beginning in 2017, and is not expected to have a significant impact on our consolidated financial statements. ASU 2016-15 "Statement of Cash Flows (Topic 230)" ("ASU 2016-15") is intended to reduce the diversity in practice around how certain transactions are classified within the statement of cash flows. ASU 2016-15 will be effective for us on January 1, 2018 and is not expected to have a significant impact on our consolidated financial statements. ASU 2016-13 "Financial Instruments - Credit Losses (Topic 326)" ("ASU 2016-13") requires an entity to utilize a new impairment model known as the current expected credit loss ("CECL") model to estimate its lifetime "expected credit loss" and record an allowance that, when deducted from the amortized cost basis of the financial asset, presents the net amount expected to be collected on the financial asset. The CECL model is expected to result in more timely recognition of credit losses. ASU 2016-13 also requires new disclosures for financial assets measured at amortized cost, loans and available-for-sale debt securities. Entities will apply the standard's provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. ASU 2016-13 will be effective for us on January 1, 2020. We are evaluating the impact adoption of ASU 2016-13 will have on our consolidated financial statements and disclosures. While we are currently unable to reasonably estimate the impact of adopting ASU 2016-13, we expect that the impact of adoption could be significantly influenced by the composition, characteristics and quality of our loan portfolio as well as the prevailing economic conditions and forecasts as of the adoption date. As part of our evaluation process, we have established a steering committee and working group that includes individuals from various functional areas to assess processes, portfolio segmentation, systems requirements and needed resources to implement this new accounting standard. ASU 2016-02 " Leases (Topic 842) " ("ASU 2016-02") requires that lessees and lessors recognize lease assets and lease liabilities on the balance sheet and disclose key information about leasing arrangements. ASU 2016-02 will be effective for us on January 1, 2019. ASU 2016-02 provides for a modified retrospective transition approach requiring lessees to recognize and measure leases on the balance sheet at the beginning of the earliest period presented with the option to elect certain practical expedients. We are currently evaluating a third party software solution to assist with the accounting under the new standard. Our operating leases relate primarily to office space and bank branches. We expect recorded assets and liabilities to increase upon adoption of the standard as it relates to operating leases in which we are the lessee. See Note 17 - Commitments and Contingencies for a summary of minimum future lease payments under operating leases as of December 31, 2017. ASU 2016-01, "Financial Instruments - Overall (Subtopic 825-10): Recognition of Financial Assets and Financial Liabilities," ("ASU 2016-01") makes targeted amendments to the guidance for recognition, measurement, presentation and disclosure of financial instruments. ASU 2016-01 will be effective for us on January 1, 2018. ASU 2016-01 requires equity investments, other than equity method investments, to be measured at fair value with changes in fair value recognized in net income. At adoption, any cumulative change in the fair value of these equity securities previously recognized in accumulated other comprehensive income will be recorded as an adjustment to the opening balance of retained earnings, and any further changes to their fair value will be recorded in net income. We do not expect the new guidance to have a material impact on our consolidated financial statements. ASU 2016-01 also emphasizes the existing requirement to use exit prices to measure fair value for disclosure purposes and clarifies that entities should not make use of practicability exception in determining the fair value of loans. Accordingly, we will refine the calculation used to determine the disclosed fair value of our loans held for investment portfolio as part of adopting the standard. ASU 2014-09 "Revenue from Contracts with Customers (Topic 606)" ("ASU 2014-09") implements a common revenue standard that clarifies the principles for recognizing revenue. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 establishes a five-step model which entities must follow to recognize revenue and removes inconsistencies and weaknesses in existing guidance. The guidance does not apply to revenue associated with financial instruments, including loans and securities that are accounted for under other GAAP, which comprises a significant portion of our revenue stream. We will adopt ASU 2014-09 effective January 1, 2018 and expect adoption to have no material effect on how we recognize revenue. We also anticipate adoption to have no material impact to our consolidated financial statements and disclosures.

Operations and Summary of Sig31

Operations and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Nature of Business	Organization and Nature of Business Texas Capital Bancshares, Inc. (the "Company”), a Delaware corporation, was incorporated in November 1996 and commenced banking operations in December 1998. The consolidated financial statements of the Company include the accounts of Texas Capital Bancshares, Inc. and its wholly owned subsidiary, Texas Capital Bank, National Association (the "Bank”). We are primarily a secured lender and serve the needs of commercial businesses and successful professionals and entrepreneurs located in Texas as well as operate several lines of business serving a regional or national clientèle of commercial borrowers. We are primarily a secured lender, with our greatest concentration of loans in Texas.
Basis of Presentation	Basis of Presentation Our accounting and reporting policies conform to accounting principles generally accepted in the United States ("GAAP") and to generally accepted practices within the banking industry. Certain prior period balances have been reclassified to conform to the current period presentation. In that regard, ASU 2016-09, "Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting," ("ASU 2016-09") became effective for us on January 1, 2017. ASU 2016-09 requires that excess tax benefits and deficiencies be recognized as a component of income taxes within the income statement. Additionally, ASU 2016-09 requires that all income tax-related cash flows resulting from share-based payments be reported as operating activities in the statement of cash flows. Previously, income tax benefits at award settlement were reported as a reduction to operating cash flows and an increase to financing cash flows to the extent that those benefits exceeded the income tax benefits reported in earnings during the award's vesting period. We have elected to apply that change in cash flow presentation on a prospective basis. ASU 2016-09 also requires that companies make an accounting policy election regarding forfeitures, to either estimate the number of awards that are expected to vest or account for them when they occur. We have elected to recognize forfeitures as they occur. The impact of this change and that of the remaining provisions of ASU 2016-09 did not have a significant impact on our financial statements.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates. The allowance for loan losses, the allowance for off-balance sheet credit losses, the fair value of stock-based compensation awards, the fair value of mortgage servicing rights ("MSRs"), the fair value of financial instruments and the status of contingencies are particularly susceptible to significant change.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents include amounts due from banks, interest-bearing deposits and Federal funds sold.
Securities	Securities Securities are classified as trading, available-for-sale or held-to-maturity. Management classifies securities at the time of purchase and re-assesses such designation at each balance sheet date; however, transfers between categories from this re-assessment are rare. Trading Account Securities acquired for resale in anticipation of short-term market movements are classified as trading, with realized and unrealized gains and losses recognized in income. To date, we have not had any activity in our trading account. Available-for-Sale Debt securities are classified as held-to-maturity when we have the positive intent and ability to hold the securities to maturity. Held-to-maturity securities are stated at amortized cost. Debt securities not classified as held-to-maturity or trading and marketable equity securities not classified as trading are classified as available-for-sale. Available-for-sale securities are stated at fair value, with the unrealized gains and losses reported in a separate component of accumulated other comprehensive income (loss), net of tax. The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity, or in the case of mortgage-backed securities, over the estimated life of the security. Such amortization and accretion is included in interest income from securities. Realized gains and losses and declines in value judged to be other-than-temporary are included in gain (loss) on sale of securities. The cost of securities sold is based on the specific identification method. All securities are available-for-sale as of December 31, 2017 and 2016 .
Loans	Loans Loans Held for Sale Through our MCA program, we commit to purchase residential mortgage loans from independent correspondent lenders and deliver those loans into the secondary market via whole loan sales to independent third parties or in securitization transactions to third parties such as Ginnie Mae or to GSEs such as Fannie Mae or Freddie Mac. In some cases, we retain the mortgage servicing rights. Once purchased, these loans are classified as held for sale and are carried at fair value pursuant to our election of the fair value option in accordance with Accounting Standards Codification 825, Financial Instruments ("ASC 825"). At the commitment date, we enter into a corresponding forward sale commitment with a third party, typically Ginnie Mae or a GSE, to deliver the loans within a specified timeframe. The estimated gain/loss for the entire transaction (from initial purchase commitment to final delivery of loans) is recorded as an asset or liability. Fair value is derived from observable current market prices, when available, and includes the fair value of the mortgage servicing rights. Adjustments to reflect unrealized gains and losses resulting from changes in fair value and realized gains and losses upon ultimate sale of the loans are classified as other non-interest income in the consolidated statements of income and other comprehensive income. Pursuant to Ginnie Mae servicing guidelines, we have the unilateral right, but not the obligation, to repurchase certain delinquent loans securitized in Ginnie Mae pools, if they meet defined delinquent loan criteria. Once the delinquency criteria have been met, and regardless of whether the repurchase option has been exercised, we account for these loans as if they had been repurchased and recognize the loans and a corresponding liability as held for sale and other liabilities, respectively, in the consolidated balance sheets. If the loans are actually repurchased, the liability is cash settled and the loans continue to be reported as held for sale. As an approved lender, we may collect losses incurred on repurchased loans through a claims process with the government agency. Loans Held for Investment Loans held for investment (which include equipment leases accounted for as financing leases) are stated at the amount of unpaid principal reduced by deferred income (net of costs). Interest on loans is recognized using the simple-interest method on the daily balances of the principal amounts outstanding. Loan origination fees, net of direct loan origination costs, and commitment fees, are deferred and amortized as an adjustment to yield over the life of the loan, or over the commitment period, as applicable. A loan held for investment is considered impaired when, based on current information and events, it is probable that we will be unable to collect all amounts due (both principal and interest) according to the terms of the loan agreement. Reserves on impaired loans are measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate or the fair value of the underlying collateral, less cost to sell. Impaired loans, or portions thereof, are charged off when a confirmed loss exists. The accrual of interest on loans is discontinued when there is a clear indication that the borrower’s cash flow may not be sufficient to meet payments as they become due, which is generally when a loan is 90 days past due. When a loan is placed on non-accrual status, all previously accrued and unpaid interest is reversed. Interest income is subsequently recognized on a cash basis as long as the remaining book balance of the asset is deemed to be collectible. If collectability is questionable, then cash payments are applied to principal. A loan is placed back on accrual status when both principal and interest are current and it is probable that we will be able to collect all amounts due (both principal and interest) according to the terms of the loan agreement. Loans held for investment includes legal ownership interests in mortgage loans that we purchase through our mortgage warehouse lending division. The ownership interests are purchased from unaffiliated mortgage originators who are seeking additional funding through sale of the undivided ownership interests to facilitate their ability to originate loans. The mortgage originator has no obligation to offer and we have no obligation to purchase these interests. The originator closes mortgage loans consistent with underwriting standards established by approved investors, and, at the time of the sale to the investor, our ownership interest and that of the originator are delivered by us to the investor selected by the originator and approved by us. We typically purchase up to a 99% ownership interest in each mortgage with the originator owning the remaining percentage. These mortgage ownership interests are generally held by us for a period of less than 30 days and more typically 10-20 days. Because of conditions in agreements with originators designed to reduce transaction risks, under ASC 860, Transfers and Servicing of Financial Assets (“ASC 860”), the ownership interests do not qualify as participating interests. Under ASC 860, the ownership interests are deemed to be loans to the originators and payments we receive from investors are deemed to be payments made by or on behalf of the originator to repay the loan deemed made to the originator. Because we have an actual, legal ownership interest in the underlying residential mortgage loan, these interests are not extensions of credit to the originators that are secured by the mortgage loans as collateral. Due to market conditions or events of default by the investor or the originator, we could be required to purchase the remaining interests in the mortgage loans and hold them beyond the expected 10-20 days. Mortgage loans acquired under these conditions would require mark-to-market adjustments to income and could require future allocations of the allowance for loan losses or be subject to charge off in the event the loans become impaired. Mortgage loan interests purchased and disposed of as expected receive no allocation of the allowance for loan losses due to the minimal loss experience with these assets.
Allowance for Loan Losses	Allowance for Loan Losses The allowance for loan losses is comprised of general reserves, specific reserves for impaired loans and an additional qualitative reserve based on our estimate of losses inherent in the portfolio at the balance sheet date, but not yet identified with specified loans. We regularly evaluate our allowance for loan losses to maintain an appropriate level to absorb estimated loan losses inherent in the loan portfolio. Factors contributing to the determination of the allowance include the creditworthiness of the borrower, changes in the value of pledged collateral, and general economic conditions. All loan commitments rated substandard or worse and greater than $500,000 are specifically reviewed for loss potential. For loans deemed to be impaired, a specific allocation is assigned based on the losses expected to be realized from those loans. For purposes of determining the general reserve, the portfolio is segregated by product types to recognize differing risk profiles among categories, and then further segregated by credit grades. Credit grades are assigned to all loans. Each credit grade is assigned a risk factor, or reserve allocation percentage. These risk factors are multiplied by the outstanding principal balance and risk-weighted by product type to calculate the required reserve. A similar process is employed to calculate a reserve assigned to off-balance sheet commitments, specifically unfunded loan commitments and letters of credit, and any needed reserve is recorded in other liabilities. Even though portions of the allowance may be allocated to specific loans, the entire allowance is available for any credit that, in management’s judgment, should be charged off. We have several pass credit grades that are assigned to loans based on varying levels of risk, ranging from credits that are secured by cash or marketable securities, to watch credits which have all the characteristics of an acceptable credit risk but warrant more than the normal level of monitoring. Within our criticized/classified credit grades are special mention, substandard, and doubtful. Special mention loans are those that are currently protected by the sound worth and paying capacity of the borrower, but that are potentially weak and constitute an additional credit risk. These loans have the potential to deteriorate to a substandard grade due to the existence of financial or administrative deficiencies. Substandard loans have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They are characterized by the distinct possibility that we will sustain some loss if the deficiencies are not corrected. Some substandard loans are inappropriately protected by sound worth and paying capacity of the borrower and of the collateral pledged and may be considered impaired. Substandard loans can be accruing or can be on non-accrual depending on the circumstances of the individual loans. Loans classified as doubtful have all the weaknesses inherent in substandard loans with the added characteristics that the weaknesses make collection or liquidation in full highly questionable and improbable. The possibility of loss is extremely high. All doubtful loans are on non-accrual. The allowance allocation percentages assigned to each credit grade have been developed based primarily on an analysis of our historical loss rates. The allocations are adjusted for certain qualitative factors, including general economic conditions, changes in credit policies and lending standards. Changes in the trend and severity of problem loans can cause the estimation of losses to differ from past experience. In addition, the allowance considers the results of reviews performed by our Credit Review group as reflected in their confirmations of assigned credit grades within the portfolio. The portion of the allowance that is not derived by the allowance allocation percentages compensates for the uncertainty and complexity in estimating loan and lease losses including factors and conditions that may not be fully reflected in the determination and application of the allowance allocation percentages. Examples of risks that support the Bank's maintaining an additional qualitative reserve include economic uncertainties and unpredictable factors that produce losses, including those resulting from borrowers' submission of financial information or inaccurate certification of collateral values. These situations, while not common, do not necessarily correlate well with historical loss trends or general economic conditions. Our methodology used to calculate the allowance considers historical losses, however, the historical loss rates for specific product types or credit risk grades may not fully incorporate the effects of uncertainty regarding the economy or other unpredictable events. The methodology used in the periodic review of the appropriateness of the allowance, which is performed at least quarterly, is designed to be dynamic and responsive to changes in portfolio credit quality. The changes are reflected in the general allowance and in specific reserves as the collectability of classified loans is evaluated with new information. As our portfolio has matured, historical loss ratios have been closely monitored, and our reserve appropriateness relies primarily on our loss history. The review of the appropriateness of the allowance is performed by executive management and presented to the audit and risk committees of our board of directors for their review. The committees report to the board as part of the board's review on a quarterly basis of the Company's consolidated financial statements.
Other Real Estate Owned	Other Real Estate Owned Other real estate owned (“OREO”), which is included in other assets on the consolidated balance sheet, consists of real estate that has been foreclosed. Real estate that has been foreclosed is recorded at the fair value of the real estate, less selling costs, through a charge to the allowance for loan losses, if necessary. Subsequent write-downs required for declines in value are recorded through a valuation allowance, or taken directly to the asset, charged to other non-interest expense.
Premises and Equipment	Premises and Equipment Premises and equipment are stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which range from three to ten years . Gains or losses on disposals of premises and equipment are included in other non-interest income in the consolidated income statements.
Marketing and Software	Marketing and Software Marketing costs are expensed as incurred. Ongoing maintenance and enhancements of websites are expensed as incurred. Costs incurred in connection with development or purchase of internal use software are capitalized and amortized over a period not to exceed five years . Internal use software costs are included in other assets in the consolidated balance sheets.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Intangible assets are acquired assets that lack physical substance but can be distinguished from goodwill because of contractual or other legal rights or because the asset is capable of being sold or exchanged either on its own or in combination with a related contract, asset, or liability. Our intangible assets relate primarily to loan customer relationships. Intangible assets with definite useful lives are amortized over their estimated life. Goodwill and intangible assets are tested for impairment in October on an annual basis or whenever events or changes in circumstances indicate the carrying amount of the assets may not be recoverable from future undiscounted cash flows. If impaired, the assets are recorded at fair value.
Segment Reporting	Segment Reporting We have determined that all of our lending divisions and subsidiaries meet the aggregation criteria of ASC 280, Segment Reporting , since all offer similar products and services, operate with similar processes, and have similar customers.
Stock-based Compensation	Stock-based Compensation We account for all stock-based compensation transactions in accordance with ASC 718, Compensation — Stock Compensation (“ASC 718”), which requires that stock compensation transactions be recognized as compensation expense in the consolidated statement of income and other comprehensive income based on their fair values on the measurement date, which is the date of the grant.
Accumulated Other Comprehensive Income	Accumulated Other Comprehensive Income Unrealized gains or losses on our available-for-sale securities (after applicable income tax expense or benefit) are included in accumulated other comprehensive income, net. Accumulated other comprehensive income (loss), net is reported in the accompanying consolidated statements of stockholders’ equity and consolidated statements of income and other comprehensive income.
Income Taxes	Income Taxes The Company and its subsidiary file a consolidated federal income tax return. We utilize the liability method in accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based upon the difference between the values of the assets and liabilities as reflected in the financial statements and their related tax basis using enacted tax rates in effect for the year in which the differences are expected to be recovered or settled. As changes in tax law or rates are enacted, deferred tax assets and liabilities are adjusted through the provision for income taxes. A valuation allowance is provided against deferred tax assets unless it is more likely than not that such deferred tax assets will be realized.
Basic and Diluted Earnings Per Common Share	Basic and Diluted Earnings Per Common Share Basic earnings per common share is based on net income available to common stockholders divided by the weighted-average number of common shares outstanding during the period excluding non-vested stock. Diluted earnings per common share include the dilutive effect of stock options and non-vested stock awards granted using the treasury stock method. A reconciliation of the weighted-average shares used in calculating basic earnings per common share and the weighted average common shares used in calculating diluted earnings per common share for the reported periods is provided in Note 15 — Earnings Per Share.
Fair Values of Financial Instruments	Fair Values of Financial Instruments ASC 820, Fair Value Measurements and Disclosures (“ASC 820”), defines fair value, establishes a framework for measuring fair value under GAAP and enhances disclosures about fair value measurements. In general, fair values of financial instruments are based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based on estimates using present value or other valuation techniques. Those techniques are significantly affected by the assumptions used, including the discount rate and estimates of future cash flows.
Mortgage Servicing Rights	Mortgage Servicing Rights Mortgage servicing rights are created by selling purchased or originated mortgage loans with servicing rights retained. We identify classes of servicing rights based upon the nature of the underlying assumptions used to value the asset along with the risks associated with the underlying asset. Based upon these criteria we have one class of MSRs, residential. Originated MSRs are recognized based on the estimated fair value of the mortgage loans and the related servicing rights at the date of sale using values derived from a valuation model managed by an independent third party. MSRs are amortized proportionally over the estimated life of the projected net servicing revenue and are periodically evaluated for impairment. MSRs are reported on the consolidated balance sheets at amortized cost, less a valuation allowance if the fair value of identified strata within the MSR portfolio are determined to have a fair value that is less than amortized cost. Loan servicing fee income represents income earned for servicing mortgage loans owned by investors and includes mortgage servicing fees and other ancillary servicing income. Servicing fees are recorded as income when earned and are reported in other non-interest income on the consolidated statements of income and other comprehensive income. For additional information on MSRs, see Note 5 - Certain Transfers of Financial Assets.
Guarantees	The Company has undertaken certain guarantee obligations in the ordinary course of business which include liabilities with off-balance sheet risk. We consider the following arrangements to be guarantees: commitments to extend credit, standby letters of credit and indemnification agreements included within third party contractual arrangements. For additional information on commitments and contingencies, see Note 13 - Financial Instruments with Off-Balance Sheet Risk.
Derivative Financial Instruments	Derivative Financial Instruments All contracts that satisfy the definition of a derivative are recorded at fair value in other assets and other liabilities in the consolidated balance sheets. We record the derivatives on a net basis when a right of offset exists, based on transactions with a single counterparty that are subject to a legally enforceable master netting agreement. For additional information on derivative financial instruments, see Note 20 - Derivative Financial Instruments.

Securities (Tables)

Securities (Tables)	12 Months Ended
	Dec. 31, 2017
Available-for-sale Securities [Abstract]
Summary of securities	The following is a summary of securities (in thousands): December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Available-for-sale securities: Residential mortgage-backed securities $ 10,297 $ 648 $ — $ 10,945 Equity securities(1) 12,556 425 (415 ) 12,566 $ 22,853 $ 1,073 $ (415 ) $ 23,511 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Available-for-sale securities: Residential mortgage-backed securities $ 14,680 $ 972 $ — $ 15,652 Municipals 275 — — 275 Equity securities(1) 9,280 27 (360 ) 8,947 $ 24,235 $ 999 $ (360 ) $ 24,874 (1) Equity securities consist of Community Reinvestment Act funds and investments related to our non-qualified deferred compensation plan.
Schedule of amortized cost and estimated fair value of securities	The amortized cost and estimated fair value of securities are presented below by contractual maturity (in thousands, except percentage data): December 31, 2017 Less Than One Year After One Through Five Years After Five Through Ten Years After Ten Years Total Available-for-sale: Residential mortgage-backed securities:(1) Amortized cost $ 409 $ 819 $ 1,502 $ 7,567 $ 10,297 Estimated fair value 418 916 1,636 7,975 10,945 Weighted average yield(3) 4.59 % 6.02 % 5.32 % 3.45 % 3.97 % Equity securities:(4) Amortized cost 12,556 — — — 12,556 Estimated fair value 12,566 — — — 12,566 Total available-for-sale securities: Amortized cost $ 22,853 Estimated fair value $ 23,511 December 31, 2016 Less Than One Year After One Through Five Years After Five Through Ten Years After Ten Years Total Available-for-sale: Residential mortgage-backed securities:(1) Amortized cost $ 9 $ 2,047 $ 3,147 $ 9,477 $ 14,680 Estimated fair value 9 2,104 3,495 10,044 15,652 Weighted average yield(3) 5.50 % 4.70 % 5.55 % 2.84 % 3.68 % Municipals:(2) Amortized cost 275 — — — 275 Estimated fair value 275 — — — 275 Weighted average yield(3) 5.61 % — — — 5.61 % Equity securities:(4) Amortized cost 9,280 — — — 9,280 Estimated fair value 8,947 — — — 8,947 Total available-for-sale securities: Amortized cost $ 24,235 Estimated fair value $ 24,874 (1) Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without prepayment penalties. (2) Yields have been adjusted to a tax equivalent basis assuming a 35% federal tax rate. (3) Yields are calculated based on amortized cost. (4) These equity securities do not have a stated maturity.
Schedule of investment securities that have been in a continuous unrealized loss position for less or more than 12 months	The following table discloses, as of December 31, 2017 and December 31, 2016 , our investment securities that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for 12 or more months (in thousands): December 31, 2017 Less Than 12 Months 12 Months or Longer Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Equity securities $ 1,015 $ (6 ) $ 6,091 $ (409 ) $ 7,106 $ (415 ) December 31, 2016 Less Than 12 Months 12 Months or Longer Total Fair Unrealized Fair Unrealized Fair Unrealized Equity securities $ 1,015 $ (6 ) $ 6,146 $ (354 ) $ 7,161 $ (360 )

Loans and Allowance for Credi33

Loans and Allowance for Credit Losses (Tables)	12 Months Ended
	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Schedule of loans held for investments	Loans held for investment are summarized by category as follows (in thousands): December 31, 2017 2016 Commercial $ 9,189,811 $ 7,291,545 Mortgage finance 5,308,160 4,497,338 Construction 2,166,208 2,098,706 Real estate 3,794,577 3,462,203 Consumer 48,684 34,587 Equipment leases 264,903 185,529 Gross loans held for investment 20,772,343 17,569,908 Deferred income (net of direct origination costs) (97,931 ) (71,559 ) Allowance for loan losses (184,655 ) (168,126 ) Total loans held for investment $ 20,489,757 $ 17,330,223
Schedule of the credit risk profile of loan portfolio by internally assigned grades and nonaccrual status	The following tables summarize the credit risk profile of our loan portfolio by internally assigned grades and non-accrual status as of December 31, 2017 and 2016 (in thousands): Commercial Mortgage Finance Construction Real Estate Consumer Equipment Leases Total December 31, 2017 Grade: Pass $ 8,967,471 $ 5,308,160 $ 2,152,654 $ 3,706,541 $ 48,591 $ 249,865 $ 20,433,282 Special mention 19,958 — 13,554 53,652 — 495 87,659 Substandard- accruing 102,651 — — 32,671 93 14,543 149,958 Non-accrual 99,731 — — 1,713 — — 101,444 Total loans held for investment $ 9,189,811 $ 5,308,160 $ 2,166,208 $ 3,794,577 $ 48,684 $ 264,903 $ 20,772,343 Commercial Mortgage Finance Construction Real Estate Consumer Equipment Leases Total December 31, 2016 Grade: Pass $ 6,941,310 $ 4,497,338 $ 2,074,859 $ 3,430,346 $ 34,249 $ 181,914 $ 17,160,016 Special mention 69,447 — 10,901 21,932 — 3,532 105,812 Substandard-accruing 115,848 — 12,787 7,516 138 — 136,289 Non-accrual 164,940 — 159 2,409 200 83 167,791 Total loans held for investment $ 7,291,545 $ 4,497,338 $ 2,098,706 $ 3,462,203 $ 34,587 $ 185,529 $ 17,569,908
Schedule of activity in the reserve for loan losses by portfolio segment	Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories. Commercial Mortgage Finance Construction Real Estate Consumer Equipment Leases Additional Qualitative Reserve Total December 31, 2017 Allowance for loan losses Beginning balance $ 128,768 $ — $ 13,144 $ 19,149 $ 241 $ 1,124 $ 5,700 $ 168,126 Provision for loan losses 19,590 — 6,084 15,353 226 2,408 2,690 46,351 Charge-offs 34,145 — 59 290 180 — — 34,674 Recoveries 4,593 — 104 75 70 10 — 4,852 Net charge-offs (recoveries) 29,552 — (45 ) 215 110 (10 ) — 29,822 Ending balance $ 118,806 $ — $ 19,273 $ 34,287 $ 357 $ 3,542 $ 8,390 $ 184,655 Period end amount allocated to: Loans individually evaluated for impairment $ 24,316 $ — $ — $ 101 $ — $ — $ — $ 24,417 Loans collectively evaluated for impairment 94,490 — 19,273 34,186 357 3,542 8,390 160,238 Ending balance $ 118,806 $ — $ 19,273 $ 34,287 $ 357 $ 3,542 $ 8,390 $ 184,655 Commercial Mortgage Finance Construction Real Estate Consumer Equipment Leases Additional Qualitative Reserve Total December 31, 2016 Allowance for loan losses Beginning balance $ 112,446 $ — $ 6,836 $ 13,381 $ 338 $ 3,931 $ 4,179 $ 141,111 Provision for loan losses 63,516 — 6,274 6,233 (71 ) (2,884 ) 1,521 74,589 Charge-offs 56,558 — — 528 47 — — 57,133 Recoveries 9,364 — 34 63 21 77 — 9,559 Net charge-offs (recoveries) 47,194 — (34 ) 465 26 (77 ) — 47,574 Ending balance $ 128,768 $ — $ 13,144 $ 19,149 $ 241 $ 1,124 $ 5,700 $ 168,126 Period end amount allocated to: Loans individually evaluated for impairment $ 34,405 $ — $ 24 $ 133 $ 30 $ 13 $ — $ 34,605 Loans collectively evaluated for impairment 94,363 — 13,120 19,016 211 1,111 5,700 133,521 Ending balance $ 128,768 $ — $ 13,144 $ 19,149 $ 241 $ 1,124 $ 5,700 $ 168,126
Allowance for Credit Losses on Financing Receivables [Table Text Block]	The table below presents the activity in the allowance for off-balance sheet credit losses related to losses on unfunded commitments for the years ended December 31, 2017 and 2016 (in thousands). This allowance is recorded in other liabilities in the consolidated balance sheet. Year Ended December 31, 2017 2016 Beginning balance $ 11,422 $ 9,011 Provision for off-balance sheet credit losses (2,351 ) 2,411 Ending balance $ 9,071 $ 11,422
Schedule of recorded investment in loans related to each balance in the allowance for loan losses	Our recorded investment in loans as of December 31, 2017 and 2016 related to each balance in the allowance for loan losses by portfolio segment and disaggregated on the basis of our impairment methodology was as follows (in thousands): Commercial Mortgage Finance Construction Real Estate Consumer Equipment Leases Total December 31, 2017 Loans individually evaluated for impairment $ 100,676 $ — $ — $ 2,008 $ — $ — $ 102,684 Loans collectively evaluated for impairment 9,089,135 5,308,160 2,166,208 3,792,569 48,684 264,903 20,669,659 Total $ 9,189,811 $ 5,308,160 $ 2,166,208 $ 3,794,577 $ 48,684 $ 264,903 $ 20,772,343 Commercial Mortgage Finance Construction Real Estate Consumer Equipment Leases Total December 31, 2016 Loans individually evaluated for impairment $ 166,669 $ — $ 159 $ 3,751 $ 200 $ 83 $ 170,862 Loans collectively evaluated for impairment 7,124,876 4,497,338 2,098,547 3,458,452 34,387 185,446 17,399,046 Total $ 7,291,545 $ 4,497,338 $ 2,098,706 $ 3,462,203 $ 34,587 $ 185,529 $ 17,569,908
Schedule of impaired loans, by portfolio class	The following tables detail our impaired loans, by portfolio class, as of December 31, 2017 and 2016 (in thousands): December 31, 2017 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized With no related allowance recorded: Commercial Business loans $ 16,835 $ 18,257 $ — $ 22,964 $ — Energy loans 21,426 22,602 — 36,579 — Construction Market risk — — — — — Real estate Market risk — — — — — Commercial 1,096 1,096 — 2,166 — Secured by 1-4 family — — — — — Consumer — — — — — Equipment leases — — — — — Total impaired loans with no allowance recorded $ 39,357 $ 41,955 $ — $ 61,709 $ — With an allowance recorded: Commercial Business loans $ 18,645 $ 19,020 $ 2,544 $ 16,960 $ — Energy loans 43,770 55,875 21,772 50,867 6 Construction Market risk — — — 27 — Real estate Market risk 295 295 6 485 — Commercial 499 499 75 166 — Secured by 1-4 family 118 118 20 516 — Consumer — — — 33 — Equipment leases — — — 14 — Total impaired loans with an allowance recorded $ 63,327 $ 75,807 $ 24,417 $ 69,068 $ 6 Combined: Commercial Business loans $ 35,480 $ 37,277 $ 2,544 $ 39,924 $ — Energy loans 65,196 78,477 21,772 87,446 6 Construction Market risk — — — 27 — Real estate Market risk 295 295 6 485 — Commercial 1,595 1,595 75 2,332 — Secured by 1-4 family 118 118 20 516 — Consumer — — — 33 — Equipment leases — — — 14 — Total impaired loans $ 102,684 $ 117,762 $ 24,417 $ 130,777 $ 6 December 31, 2016 Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized With no related allowance recorded: Commercial Business loans $ 23,868 $ 27,992 $ — $ 12,361 $ — Energy loans 46,753 54,522 — 54,075 — Construction Market risk — — — 2,778 — Real estate Market risk — — — — — Commercial 2,083 2,083 — 4,483 38 Secured by 1-4 family — — — — — Consumer — — — — — Equipment leases — — — 403 — Total impaired loans with no allowance recorded $ 72,704 $ 84,597 $ — $ 74,100 $ 38 With an allowance recorded: Commercial Business loans $ 21,303 $ 21,303 $ 7,055 $ 22,277 $ — Energy loans 74,745 88,987 27,350 73,637 24 Construction Market risk 159 159 24 53 — Real estate Market risk 1,342 1,342 20 3,000 — Commercial — — — — — Secured by 1-4 family 326 326 113 435 — Consumer 200 200 30 67 — Equipment leases 83 83 13 548 — Total impaired loans with an allowance recorded $ 98,158 $ 112,400 $ 34,605 $ 100,017 $ 24 Combined: Commercial Business loans $ 45,171 $ 49,295 $ 7,055 $ 34,638 $ — Energy loans 121,498 143,509 27,350 127,712 24 Construction Market risk 159 159 24 2,831 — Real estate Market risk 1,342 1,342 20 3,000 — Commercial 2,083 2,083 — 4,483 38 Secured by 1-4 family 326 326 113 435 — Consumer 200 200 30 67 — Equipment leases 83 83 13 951 — Total impaired loans $ 170,862 $ 196,997 $ 34,605 $ 174,117 $ 62
Schedule of an age analysis of accruing past due loans	The table below provides an age analysis of our loans held for investment as of December 31, 2017 (in thousands): 30-59 Days Past Due 60-89 Days Past Due Greater Than 90 Days(1) Total Past Due Non-accrual Current Total Commercial Business loans $ 12,346 $ 13,029 $ 6,984 $ 32,359 $ 34,535 $ 7,992,918 $ 8,059,812 Energy 1,100 — — 1,100 65,196 1,063,703 1,129,999 Mortgage finance loans — — — — — 5,308,160 5,308,160 Construction Market risk 239 — — 239 — 2,098,446 2,098,685 Commercial — — — — — 35,786 35,786 Secured by 1-4 family 1,635 — — 1,635 — 30,102 31,737 Real estate Market risk 1,724 295 — 2,019 — 2,681,527 2,683,546 Commercial — — — — 1,595 839,787 841,382 Secured by 1-4 family 174 139 1,392 1,705 118 267,826 269,649 Consumer 100 74 — 174 — 48,510 48,684 Equipment leases 636 16 53 705 — 264,198 264,903 Total loans held for investment $ 17,954 $ 13,553 $ 8,429 $ 39,936 $ 101,444 $ 20,630,963 $ 20,772,343 (1) Loans past due 90 days and still accruing includes premium finance loans of $5.5 million . These loans are generally secured by obligations of insurance carriers to refund premiums on canceled insurance policies. The refund of premiums from the insurance carriers can take 180 days or longer from the cancellation date.
Schedule of loans that have been restructured	The following table provides information on how loans were modified as restructured loans during the year ended December 31, 2017 and 2016 (in thousands): December 31, 2017 2016 Extended maturity $ 712 $ — Adjusted payment schedule 6,928 — Combination of maturity extension and payment schedule adjustment — 12,236 Total $ 7,640 $ 12,236 The following tables summarize, as of December 31, 2017 and 2016 , loans that have been restructured during 2017 and 2016 (in thousands, except number of contracts): December 31, 2017 Number of Contracts Pre-Restructuring Outstanding Recorded Investment Post-Restructuring Outstanding Recorded Investment Commercial business loans 3 $ 7,527 $ 7,640 Energy loans 1 $ 1,070 $ — Total new restructured loans in 2017 4 $ 8,597 $ 7,640 December 31, 2016 Number of Contracts Pre-Restructuring Outstanding Recorded Investment Post-Restructuring Outstanding Recorded Investment Energy loans 2 $ 14,235 $ 12,236 Total new restructured loans in 2016 2 $ 14,235 $ 12,236

OREO and Valuation Allowance 34

OREO and Valuation Allowance for Losses on OREO (Tables)	12 Months Ended
	Dec. 31, 2017
Real Estate Owned, Disclosure of Detailed Components [Abstract]
Summary of the activity related to OREO	The table below presents a summary of the activity related to OREO (in thousands): Year ended December 31, 2017 2016 2015 Beginning balance $ 18,961 $ 278 $ 568 Additions — 18,822 1,267 Sales (1,108 ) (139 ) (1,557 ) Valuation allowance for OREO — — — Direct write-downs (6,111 ) — — Ending balance $ 11,742 $ 18,961 $ 278 When foreclosure occurs, the acquired asset is recorded at fair value less selling costs, generally based on appraised value, which may result in partial charge-off of the loan. Subsequent write-downs required for declines in value are recorded through a valuation allowance or taken directly against the asset and charged to other non-interest expense. During 2017, we recorded a $6.1 million write-down on one asset.

Certain Transfers of Financia35

Certain Transfers of Financial Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Transfers and Servicing [Abstract]
Schedule of Loans Held-for-sale [Table Text Block]	The table below presents the unpaid principal balance of loans held for sale and related fair values at December 31, 2017 and 2016 (in thousands): December 31, 2017 2016 Outstanding balance(1) $ 1,009,271 $ 980,414 Fair value(1) 1,007,695 968,929 Fair value over (under) outstanding balance $ (1,576 ) $ (11,485 ) The table below presents a reconciliation of the changes in loans held for sale for the years December 31, 2017 and 2016 (in thousands): Year Ended December 31, 2017 2016 Beginning balance $ 968,929 $ 86,075 Loans purchased 5,556,964 3,327,482 Payments and loans sold (5,524,798 ) (2,433,348 ) Change in fair value 9,909 (11,280 ) Ending balance(1) $ 1,011,004 $ 968,929
Schedule of Mortgage Servicing Rights Activity [Table Text Block]	We generally retain the right to service the loans sold, creating MSRs which are recorded as assets on our balance sheet. A summary of MSR activity for the years ended December 31, 2017 and 2016 is as follows (in thousands): Year Ended December 31, 2017 2016 MSRs: Balance, beginning of year $ 28,536 $ 423 Capitalized servicing rights 67,970 29,816 Amortization (8,356 ) (1,703 ) Balance, end of period $ 88,150 $ 28,536 Valuation allowance: Balance, beginning of year $ — $ — Increase in valuation allowance 2,823 — Balance, end of period $ 2,823 $ — MSRs, net(1) $ 85,327 $ 28,536 MSRs, fair value $ 86,321 $ 30,877
Schedule of Fair Value Assumption Used to Value Mortgage Servicing Rights Retained [Table Text Block]	December 31, 2017 and December 31, 2016 , management used the following assumptions to determine the fair value of MSRs: December 31, 2017 2016 Average discount rates 9.90 % 9.96 % Expected prepayment speeds 9.99 % 7.91 % Weighted-average life, in years 7.0 8.0
Schedule of Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets [Table Text Block]	A sensitivity analysis of changes in the fair value of our MSR portfolio resulting from certain key assumptions is presented in the following table (in thousands): December 31, 2017 2016 50 bp adverse change in prepayment speed $ (11,896 ) $ (2,833 ) 100 bp adverse change in prepayment speed (28,226 ) (6,812 )

Goodwill and Other Intangible36

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill and other intangible assets	Goodwill and other intangible assets at December 31, 2017 and 2016 are summarized as follows (in thousands): Gross Goodwill and Intangible Assets Accumulated Amortization Net Goodwill and Intangible Assets December 31, 2017 Goodwill $ 15,468 $ (374 ) $ 15,094 Intangible assets—customer relationships and trademarks 9,006 (5,060 ) 3,946 Total goodwill and intangible assets $ 24,474 $ (5,434 ) $ 19,040 December 31, 2016 Goodwill $ 15,468 $ (374 ) $ 15,094 Intangible assets—customer relationships and trademarks 9,006 (4,588 ) 4,418 Total goodwill and intangible assets $ 24,474 $ (4,962 ) $ 19,512
Schedule of estimated aggregate future amortization expense for intangible assets	The estimated aggregate future amortization expense for intangible assets remaining as of December 31, 2017 is as follows (in thousands): 2018 $ 470 2019 470 2020 432 2021 405 2022 405 Thereafter 1,764 $ 3,946

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Summary of premises and equipment	Premises and equipment at December 31, 2017 and 2016 are summarized as follows (in thousands): December 31, 2017 2016 Premises $ 25,790 $ 22,887 Furniture and equipment 32,234 24,159 58,024 47,046 Accumulated depreciation (32,848 ) (27,271 ) Total premises and equipment, net $ 25,176 $ 19,775

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2017
Deposits [Abstract]
Schedule of deposits	Deposits at December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 2016 Non-interest-bearing demand deposits $ 7,812,660 $ 7,994,201 Interest-bearing deposits Transaction 2,567,208 1,954,834 Savings 8,214,059 6,625,177 Time 529,253 442,619 Total interest-bearing deposits 11,310,520 9,022,630 Total deposits $ 19,123,180 $ 17,016,831
Schedule of maturities of interest-bearing time deposits	The scheduled maturities of interest-bearing time deposits were as follows at December 31, 2017 (in thousands): 2018 $ 492,208 2019 33,289 2020 2,817 2021 246 2022 244 2023 and after 449 $ 529,253

Borrowing Arrangements (Tables)

Borrowing Arrangements (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Summary of borrowings	The following table summarizes our borrowings at December 31, 2017 , 2016 and 2015 (in thousands): December 31, 2017 2016 2015 Balance Rate(3) Balance Rate(3) Balance Rate(3) Federal funds purchased(4) $ 359,338 1.45 % $ 101,800 0.80 % $ 74,164 0.55 % Customer repurchase agreements(1) 5,702 0.03 % 7,775 0.05 % 68,887 0.02 % FHLB borrowings(2) 2,800,000 1.35 % 2,000,000 0.61 % 1,500,000 0.31 % Subordinated notes 281,406 5.86 % 281,044 5.87 % 280,682 5.75 % Trust preferred subordinated debentures 113,406 3.55 % 113,406 2.90 % 113,406 2.47 % Total borrowings $ 3,559,852 $ 2,504,025 $ 2,037,139 Maximum outstanding at any month end $ 3,559,852 $ 2,511,579 $ 2,042,457 (1) Securities pledged for customer repurchase agreements were $7.3 million , $10.2 million and $14.2 million at December 31, 2017 , 2016 and 2015 , respectively. (2) FHLB borrowings are collateralized by a blanket floating lien on certain real estate secured loans, mortgage finance assets and also certain pledged securities. The weighted-average interest rates of FHLB borrowings for the years ended December 31, 2017 , 2016 and 2015 were 1.08% , 0.43% and 0.18% , respectively. The average balance of FHLB borrowings for the years ended December 31, 2017 , 2016 and 2015 were $1.4 billion , $1.4 billion and $1.2 billion , respectively. (3) Interest rate as of period end. (4) The weighted-average interest rates on Federal funds purchased for the years ended December 31, 2017 , 2016 and 2015 were 1.20% , 0.57% and 0.29% , respectively. The average balances of Federal funds purchased for the years ended December 31, 2017 , 2016 and 2015 were $215.9 million , $90.9 million and $98.8 million , respectively.
Summary of other borrowing capacities	The following table summarizes our other borrowing capacities net of balances outstanding at December 31, 2017 , 2016 and 2015 (in thousands): December 31, 2017 2016 2015 FHLB borrowing capacity relating to loans $ 3,890,995 $ 3,057,915 $ 4,101,396 FHLB borrowing capacity relating to securities 2,071 1,653 1,213 Total FHLB borrowing capacity $ 3,893,066 $ 3,059,568 $ 4,102,609 Unused Federal funds lines available from commercial banks $ 885,000 $ 1,118,000 $ 1,231,000 Unused Federal Reserve Borrowings capacity $ 4,114,594 $ 3,179,087 $ 2,966,702
Schedule of maturities of borrowings	The scheduled maturities of our borrowings at December 31, 2017 , excluding accrued interest, were as follows (in thousands): Within One Year After One But Within Three Years After Three But Within Five Years After Five Years Total Federal funds purchased and customer repurchase agreements $ 365,040 $ — $ — $ — $ 365,040 FHLB borrowings 2,800,000 — — — 2,800,000 Subordinated notes — — — 281,406 281,406 Trust preferred subordinated debentures — — — 113,406 113,406 Total borrowings $ 3,165,040 $ — $ — $ 394,812 $ 3,559,852

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Subordinated Borrowings [Abstract]
Schedule of details of the trust preferred subordinated debentures	As of December 31, 2017 , the details of the trust preferred subordinated debentures are summarized below (dollars in thousands): Texas Capital Texas Capital Texas Capital Texas Capital Texas Capital Date issued November 19, 2002 April 10, 2003 October 6, 2005 April 28, 2006 September 29, 2006 Trust preferred securities issued $10,310 $10,310 $25,774 $25,774 $41,238 Floating or fixed rate securities Floating Floating Floating Floating Floating Interest rate on subordinated debentures 3 month LIBOR + 3.35% 3 month LIBOR + 3.25% 3 month LIBOR + 1.51% 3 month LIBOR + 1.60% 3 month LIBOR + 1.71% Maturity date November 2032 April 2033 December 2035 June 2036 December 2036

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of income tax expense/(benefit)	Income tax expense/(benefit) consists of the following for the years ended (in thousands): Year ended December 31, 2017 2016 2015 Current: Federal $ 94,112 $ 86,612 $ 80,957 State 3,257 2,412 2,245 Total 97,369 89,024 83,202 Deferred Federal 31,276 (2,946 ) (3,561 ) State — — — Total 31,276 (2,946 ) (3,561 ) Total expense Federal 125,388 83,666 77,396 State 3,257 2,412 2,245 Total $ 128,645 $ 86,078 $ 79,641
Schedule of deferred tax assets and liabilities	(in thousands): December 31, 2017 2016 Deferred tax assets: Allowance for credit losses $ 42,213 $ 64,009 Loan origination fees 10,084 13,536 Stock compensation 4,460 5,761 Non-accrual interest 1,680 2,537 Deferred lease expense 911 1,519 Other 3,686 2,322 Total deferred tax assets 63,034 89,684 Deferred tax liabilities: Loan origination costs (1,304 ) (1,722 ) Leases (6,850 ) (7,962 ) MSRs (17,619 ) (10,973 ) Depreciation (7,354 ) (6,941 ) Unrealized gain on securities (138 ) (223 ) Other (2,068 ) (2,971 ) Total deferred tax liabilities (35,333 ) (30,792 ) Net deferred tax asset $ 27,701 $ 58,892
Reconciliation of income attributable to continuing operations	The reconciliation of our effective income tax rate to the U.S. federal statutory tax rate is as follows: Year ended December 31, 2017 2016 2015 U.S. statutory rate 35 % 35 % 35 % State taxes 1 % 1 % 1 % Non-deductible expenses 1 % 1 % 1 % Deferred tax asset write-off 5 % — % — % Non-taxable income (1 )% (1 )% (1 )% Other (1 )% — % (1 )% Effective tax rate 40 % 36 % 35 %

Stock-Based Compensation and 42

Stock-Based Compensation and Employee Benefits (Tables)	12 Months Ended
	Dec. 31, 2017
Compensation Related Costs [Abstract]
Schedule of stock appreciation rights activity	A summary of our SAR activity and related information for 2017 , 2016 and 2015 is as follows. These rights are time based and generally vest ratably over a period of five years. December 31, 2017 December 31, 2016 December 31, 2015 SARs Weighted Average Exercise Price SARs Weighted SARs Weighted SARs outstanding at beginning of year 125,863 $ 31.68 360,544 $ 25.73 445,009 $ 24.83 SARs granted — — — — — — SARs exercised (51,500 ) 33.94 (234,681 ) 22.54 (84,465 ) 20.97 SARs forfeited — — — — — — SARs outstanding at year-end 74,363 $ 30.12 125,863 $ 31.68 360,544 $ 25.73 SARs vested and exercisable at year-end 60,463 $ 26.02 94,463 $ 26.73 307,144 $ 22.49 Weighted average remaining contractual life of SARs vested 2.82 3.62 2.36 Compensation expense $ 265,000 $ 307,000 $ 367,000 Unrecognized compensation expense $ 127,000 $ 392,000 $ 699,000 Weighted average period over which unrecognized compensation expense is expected to be recognized (in years) 0.75 1.52 2.40 Fair value of shares vested during the year $ 294,000 $ 337,000 $ 436,000 Weighted average remaining contractual life of SARs currently outstanding (in years) 3.35 4.32 3.08 Intrinsic value of SARs exercised $ 3,802,000 $ 4,881,000 $ 8,291,000
Summary of status and changes in nonvested restricted stock units	A summary of our RSU activity and related information for 2017 , 2016 and 2015 is as follows. Grants of RSUs include both performance-based and time-based vesting conditions and generally vest over a three-year period. December 31, 2017 December 31, 2016 December 31, 2015 RSUs Weighted Average Grant Date Fair Value RSUs Weighted RSUs Weighted RSUs outstanding at beginning of year 425,055 $ 51.28 333,174 $ 48.60 295,165 $ 42.93 RSUs granted 121,243 80.40 213,577 51.75 145,952 51.96 RSUs exercised (102,057 ) 48.93 (94,296 ) 42.87 (95,743 ) 38.05 RSUs forfeited (20,509 ) 54.75 (27,400 ) 51.18 (12,200 ) 43.89 RSUs outstanding at year-end 423,732 $ 60.01 425,055 $ 51.28 333,174 $ 48.60 Compensation expense $ 7,790,000 $ 4,771,000 $ 4,230,000 Unrecognized compensation expense $ 18,730,000 $ 17,167,000 $ 13,038,000 Weighted average period over which unrecognized compensation expense is expected to be recognized (in years) 3.15 3.37 3.30 Weighted average remaining contractual life of RSUs currently outstanding 8.33 8.65 8.29

Financial Instruments with Of43

Financial Instruments with Off-Balance Sheet Risk (Tables)	12 Months Ended
	Dec. 31, 2017
Risks and Uncertainties [Abstract]
Schedule of financial instruments with off-balance sheet risk	At December 31, 2017 and 2016 , commitments to extend credit and standby and commercial letters of credit were as follows (in thousands): December 31, 2017 2016 Commitments to extend credit $ 6,957,847 $ 5,704,381 Standby letters of credit 230,958 171,266 At December 31, 2017 and 2016 , we had $9.1 million and $11.4 million , respectively, in allowance for off-balance sheet credit losses related to these off-balance sheet commitments recorded in other liabilities in the consolidated balance sheets.

Regulatory Restrictions (Tables

Regulatory Restrictions (Tables)	12 Months Ended
	Dec. 31, 2017
Regulatory Capital Requirements [Abstract]
Schedule of compliance with Regulatory Capital Requirements	The table below summarizes our actual and required capital ratios under the Basel III Capital Rules (dollars in thousands): Actual Minimum Capital Required - Basel III Phase-In Schedule Minimum capital Required - Basel III Fully Phased-In Required to be Considered Well Capitalized Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio As of December 31, 2017: CET1 Company $ 2,033,830 8.45 % $ 1,384,448 5.75 % $ 1,685,464 7.00 % N/A N/A Bank 1,992,152 8.28 % 1,383.475 5.75 % 1,684.231 7.00 % 1,563,929 6.50 % Total capital (to risk-weighted assets) Company 2,768,153 11.50 % 2,227.221 9.250 % 2,528.196 10.50 % N/A N/A Bank 2,567,961 10.67 % 2,225.591 9.250 % 2,526.347 10.50 % 2,406,044 10.00 % Tier 1 capital (to risk-weighted assets) Company 2,293,016 9.52 % 1,745.659 7.25 % 2,046.635 8.50 % N/A N/A Bank 2,151,338 8.94 % 1,744.382 7.25 % 2,045.138 8.50 % 1,924,835 8.00 % Tier 1 capital (to average assets)(1) Company 2,293,016 9.15 % 1,002,494 4.00 % 1,002,494 4.00 % N/A N/A Bank 2,151,338 8.59 % 1,002,144 4.00 % 1,002,144 4.00 % 1,252,680 5.00 % As of December 31, 2016: CET1 Company $ 1,841,219 8.97 % $ 1,052,205 5.125 % $ 1,437,159 7.00 % N/A N/A Bank 1,735,496 8.45 % 1,051.989 5.125 % 1,436.863 7.00 % 1,334,244 6.50 % Total capital (to risk-weighted assets) Company 2,561,663 12.48 % 1,770.766 8.625 % 2,155.715 10.50 % N/A N/A Bank 2,297,528 11.19 % 1,770.421 8.625 % 2,155.295 10.50 % 2,052,683 10.00 % Tier 1 capital (to risk-weighted assets) Company 2,101,071 10.23 % 1,360.154 6.625 % 1,745.103 8.50 % N/A N/A Bank 1,895,348 9.23 % 1,359.888 6.625 % 1,744.762 8.50 % 1,642,147 8.00 % Tier 1 capital (to average assets)(1) Company 2,101,071 9.34 % 900,268 4.00 % 900,268 4.00 % N/A N/A Bank 1,895,348 8.42 % 900,070 4.00 % 900,070 4.00 % 1,125,087 5.00 % (1) The Tier 1 capital ratio (to average assets) is not impacted by the Basel III Capital Rules; however, it should be noted that the Federal Reserve Board and the FDIC may require the Company and the Bank, respectively, to maintain a Tier 1 capital ratio (to average assets) above the required minimum.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted earnings per share	The following table presents the computation of basic and diluted earnings per share (in thousands except share data): Year ended December 31, 2017 2016 2015 Numerator: Net income $ 197,063 $ 155,119 $ 144,854 Preferred stock dividends 9,750 9,750 9,750 Net income available to common stockholders $ 187,313 $ 145,369 $ 135,104 Denominator: Denominator for basic earnings per share—weighted average shares 49,587,169 46,239,210 45,808,440 Effect of employee stock-based awards(1) 239,008 128,228 211,168 Effect of warrants to purchase common stock 433,657 398,464 418,264 Denominator for dilutive earnings per share—adjusted weighted average shares and assumed conversions 50,259,834 46,765,902 46,437,872 Basic earnings per common share $ 3.78 $ 3.14 $ 2.95 Diluted earnings per common share $ 3.73 $ 3.11 $ 2.91 (1) SARs and RSUs outstanding of 13,500 , 150,416 and 64,700 in 2017 , 2016 and 2015 , respectively, have not been included in diluted earnings per share because to do so would have been antidilutive for the periods presented.

Fair Value Disclosures (Tables)

Fair Value Disclosures (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of assets and liabilities measured at fair value	Assets and liabilities measured at fair value at December 31, 2017 and 2016 are as follows (in thousands): Fair Value Measurements Using December 31, 2017 Level 1 Level 2 Level 3 Available for sale securities:(1) Residential mortgage-backed securities $ — $ 10,945 $ — Municipals — — — Equity securities(2) 5,460 7,106 — Loans held for sale(3) — 1,007,695 — Loans held for investment(4)(6) — — 21,216 OREO(5)(6) — — 11,742 Derivative assets(7) — 16,719 — Derivative liabilities(7) — 17,377 — Non-qualified deferred compensation plan liabilities(8) 5,587 — — December 31, 2016 Available for sale securities:(1) Residential mortgage-backed securities $ — $ 15,652 $ — Municipals — 275 — Equity securities(2) 1,786 7,161 — Loans held for sale(3) — 968,929 — Loans held for investment(4)(6) — — 52,323 OREO(5)(6) — — 18,961 Derivative assets(7) — 37,878 — Derivative liabilities(7) — 26,240 — Non-qualified deferred compensation plan liabilities(8) 1,811 — — (1) Securities are measured at fair value on a recurring basis, generally monthly. (2) Equity securities consist of Community Reinvestment Act funds and investments related to our non-qualified deferred compensation plan. (3) Loans held for sale, excluding SBA loans which are carried at lower of cost or market, are measured at fair value on a recurring basis, generally monthly. (4) Includes impaired loans that have been measured for impairment at the fair value of the loan’s collateral. (5) OREO is transferred from loans to OREO at fair value less selling costs. (6) Loans held for investment and OREO are measured on a nonrecurring basis, generally annually or more often as warranted by market and economic conditions (7) Derivative assets and liabilities are measured at fair value on a recurring basis, generally quarterly. (8) Non-qualified deferred compensation plan liabilities represent the fair value of the obligation to the employee, which corresponds to the fair value of the invested assets, and are measured at fair value on a recurring basis, generally monthly.
Summary of the carrying amounts and estimated fair values of financial instruments	A summary of the carrying amounts and estimated fair values of financial instruments is as follows (in thousands): December 31, 2017 December 31, 2016 Carrying Amount Estimated Fair Value Carrying Estimated Financial assets: Level 1 inputs: Cash and cash equivalents $ 2,905,591 $ 2,905,591 $ 2,839,352 $ 2,839,352 Securities, available-for-sale 5,460 5,460 1,786 1,786 Level 2 inputs: Securities, available-for-sale 18,051 18,051 23,088 23,088 Loans held for sale 1,011,004 1,011,004 968,929 968,929 Derivative assets 16,719 16,719 37,878 37,878 Level 3 inputs: Loans held for investment, net 20,489,757 20,480,802 17,330,223 17,347,199 Financial liabilities: Level 2 inputs: Federal funds purchased 359,338 359,338 101,800 101,800 Customer repurchase agreements 5,702 5,702 7,775 7,775 Other borrowings 2,800,000 2,800,000 2,000,000 2,000,000 Subordinated notes 281,406 322,415 281,044 304,672 Derivative liabilities 17,377 17,377 26,240 26,240 Level 3 inputs: Deposits 19,123,180 19,124,121 17,016,831 17,017,221 Trust preferred subordinated debentures 113,406 113,406 113,406 113,406

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of minimum future lease payments under operating leases	Minimum future lease payments under operating leases are as follows (in thousands): Year ending December 31, Minimum Payments 2018 $ 16,446 2019 16,137 2020 15,286 2021 12,805 2022 12,138 2023 and thereafter 17,299 $ 90,111

Parent Company Only (Tables)

Parent Company Only (Tables)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Balance Sheet	Balance Sheet December 31, 2017 2016 Assets Cash and cash equivalents $ 144,635 $ 220,499 Loans held for investment (net of unearned income) 7,500 — Investment in subsidiaries 2,184,601 1,927,392 Other assets 86,300 85,560 Total assets $ 2,423,036 $ 2,233,451 Liabilities and Stockholders’ Equity Other liabilities $ 1,244 $ 1,284 Subordinated notes 108,513 108,412 Trust preferred subordinated debentures 113,406 113,406 Total liabilities 223,163 223,102 Preferred stock 150,000 150,000 Common stock 496 495 Additional paid-in capital 971,457 965,620 Retained earnings 1,077,500 893,827 Treasury stock (8 ) (8 ) Accumulated other comprehensive income 428 415 Total stockholders’ equity 2,199,873 2,010,349 Total liabilities and stockholders’ equity $ 2,423,036 $ 2,233,451
Statement of Earnings	Statement of Earnings Year ended December 31, 2017 2016 2015 Interest on loans $ 3,271 $ 3,250 $ 3,250 Dividend income 10,400 10,400 10,400 Other income 108 90 76 Total income 13,779 13,740 13,726 Other non-interest income 13 152 8 Interest expense 10,908 10,525 9,867 Salaries and employee benefits 489 431 499 Legal and professional 1,700 1,429 1,640 Other non-interest expense 1,761 1,594 1,637 Total expense 14,858 13,979 13,643 Income (loss) before income taxes and equity in undistributed income of subsidiary (1,066 ) (87 ) 91 Income tax expense (benefit) (371 ) (33 ) 33 Income (loss) before equity in undistributed income of subsidiary (695 ) (54 ) 58 Equity in undistributed income of subsidiary 194,118 151,445 141,041 Net income 193,423 151,391 141,099 Preferred stock dividends 9,750 9,750 9,750 Net income available to common stockholders $ 183,673 $ 141,641 $ 131,349
Statement of Cash Flows	Statements of Cash Flows Year ended December 31, 2017 2016 2015 (in thousands) Operating Activities Net income $ 193,423 $ 151,391 $ 141,099 Adjustments to reconcile net income to net cash used in operating activities: Equity in undistributed income of subsidiary (194,118 ) (151,445 ) (141,041 ) Amortization 101 101 100 Increase in other assets (739 ) (10 ) (2,223 ) Excess tax benefits from stock-based compensation arrangements — (2,013 ) (1,499 ) Increase in other liabilities (40 ) 165 (209 ) Net cash used in operating activities of continuing operations (1,373 ) (1,811 ) (3,773 ) Investing Activities Net increase in loans held for investment (7,500 ) — — Investments in and advances to subsidiaries (55,000 ) (57,000 ) (110,000 ) Net cash used in investing activities (62,500 ) (57,000 ) (110,000 ) Financing Activities Proceeds from sale of stock related to stock-based awards (2,241 ) (2,481 ) (1,239 ) Proceeds from sale of common stock — 236,467 — Preferred dividends paid (9,750 ) (9,750 ) (9,750 ) Net other borrowings — — — Excess tax benefits from stock-based compensation arrangements — 2,013 1,499 Net cash provided by (used in) financing activities (11,991 ) 226,249 (9,490 ) Net increase (decrease) in cash and cash equivalents (75,864 ) 167,438 (123,263 ) Cash and cash equivalents at beginning of year 220,499 53,061 176,324 Cash and cash equivalents at end of year $ 144,635 $ 220,499 $ 53,061

Derivative Financial Instrume49

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments	The notional amounts and estimated fair values of derivative positions outstanding at December 31, 2017 and 2016 are presented in the following table (in thousands): December 31, 2017 December 31, 2016 Estimated Fair Value Estimated Fair Value Notional Amount Asset Derivative Liability Derivative Notional Amount Asset Derivative Liability Derivative Non-hedging derivatives: Financial institution counterparties: Commercial loan/lease interest rate swaps $ 1,393,764 $ 4,736 $ 15,482 $ 1,144,367 $ 1,754 $ 25,421 Commercial loan/lease interest rate caps 242,700 421 7 210,996 819 — Foreign currency forward contracts 2,466 4 69 — — — Customer counterparties: Commercial loan/lease interest rate swaps 1,393,764 15,482 4,736 1,144,367 25,421 1,754 Commercial loan/lease interest rate caps 242,700 7 421 210,996 — 819 Foreign currency forward contracts 2,466 69 4 — — — Economic hedging interest rate derivatives: Loan purchase commitments 253,815 635 190 237,805 1,351 — Forward sale commitments 1,086,224 — 1,103 1,218,000 10,287 — Gross derivatives 21,354 22,012 39,632 27,994 Offsetting derivative assets/liabilities (4,635 ) (4,635 ) (1,754 ) (1,754 ) Net derivatives included in the consolidated balance sheets $ 16,719 $ 17,377 $ 37,878 $ 26,240
Schedule Of Weighted Average Interest Rate Received And Paid	The weighted-average receive and pay interest rates for interest rate swaps outstanding at December 31, 2017 and 2016 were as follows: December 31, 2017 Weighted-Average Interest Rate December 31, 2016 Received Paid Received Paid Non-hedging interest rate swaps 3.59 % 4.34 % 3.17 % 4.58 %

Quarterly Financial Data (Table

Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2017
Selected Quarterly Financial Information [Abstract]
Schedule of Quarterly Financial Information	2017 Selected Quarterly Financial Data Fourth Third Second First Interest income $ 249,519 $ 237,643 $ 208,191 $ 183,946 Interest expense 38,870 33,282 25,232 20,587 Net interest income 210,649 204,361 182,959 163,359 Provision for credit losses 2,000 20,000 13,000 9,000 Net interest income after provision for credit losses 208,649 184,361 169,959 154,359 Non-interest income 19,374 19,003 18,769 17,110 Non-interest expense 133,138 114,830 111,814 106,094 Income before income taxes 94,885 88,534 76,914 65,375 Income tax expense 50,143 29,850 25,819 22,833 Net income 44,742 58,684 51,095 42,542 Preferred stock dividends 2,437 2,438 2,437 2,438 Net income available to common stockholders $ 42,305 $ 56,246 $ 48,658 $ 40,104 Basic earnings per share: $ 0.85 $ 1.13 $ 0.98 $ 0.81 Diluted earnings per share: $ 0.84 $ 1.12 $ 0.97 $ 0.80 Average shares Basic 49,630,000 49,607,000 49,577,000 49,536,000 Diluted 50,312,000 50,251,000 50,230,000 50,234,000 2016 Selected Quarterly Financial Data Fourth Third Second First Interest income $ 188,671 $ 182,492 $ 172,442 $ 159,803 Interest expense 17,448 15,753 15,373 15,020 Net interest income 171,223 166,739 157,069 144,783 Provision for credit losses 9,000 22,000 16,000 30,000 Net interest income after provision for credit losses 162,223 144,739 141,069 114,783 Non-interest income 18,835 16,716 13,932 11,297 Non-interest expense 106,523 94,799 94,255 86,820 Income before income taxes 74,535 66,656 60,746 39,260 Income tax expense 26,149 23,931 21,866 14,132 Net income 48,386 42,725 38,880 25,128 Preferred stock dividends 2,437 2,438 2,437 2,438 Net income available to common stockholders $ 45,949 $ 40,287 $ 36,443 $ 22,690 Basic earnings per share: $ 0.97 $ 0.88 $ 0.79 $ 0.49 Diluted earnings per share: $ 0.96 $ 0.87 $ 0.78 $ 0.49 Average shares Basic 47,156,000 45,981,000 45,924,000 45,889,000 Diluted 47,760,000 46,510,000 46,438,000 46,354,000

Operations and Summary of Sig51

Operations and Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2017
Minimum
Property, Plant and Equipment [Line Items]
Useful life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Useful life	10 years
Useful life	5 years

Securities (Details)

Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale securities:
Amortized Cost	$ 22,853	$ 24,235
Gross Unrealized Gains	1,073	999
Gross Unrealized Losses	(415)	(360)
Estimated Fair Value	23,511	24,874
Residential mortgage-backed securities
Available-for-sale securities:
Amortized Cost	10,297	14,680
Gross Unrealized Gains	648	972
Gross Unrealized Losses	0	0
Estimated Fair Value	10,945	15,652
Municipals
Available-for-sale securities:
Amortized Cost		275
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Estimated Fair Value		275
Equity securities
Available-for-sale securities:
Amortized Cost	12,556	9,280
Gross Unrealized Gains	425	27
Gross Unrealized Losses	(415)	(360)
Estimated Fair Value	$ 12,566	$ 8,947

Securities (Details 1)

Securities (Details 1) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)security	Dec. 31, 2016USD ($)security	Dec. 31, 2015
Amortized cost
Amortized Cost	$ 22,853	$ 24,235
Estimated fair value
Total	$ 23,511	$ 24,874
Available-for-sale Securities, Other Disclosure Items
Federal tax rate (percent)	35.00%	35.00%	35.00%
Securities pledged as collateral	$ 8,800	$ 13,600
Number of securities in an unrealized loss position | security	2	2
Residential mortgage-backed securities
Amortized cost
Less Than One Year	$ 409	$ 9
After One Through Five Years	819	2,047
After Five Through Ten Years	1,502	3,147
After Ten Years	7,567	9,477
Amortized Cost	10,297	14,680
Estimated fair value
Less Than One Year	418	9
After One Through Five Years	916	2,104
After Five Through Ten Years	1,636	3,495
After Ten Years	7,975	10,044
Total	$ 10,945	$ 15,652
Weighted average yield
Less Than One Year	4.59%	5.50%
After One Through Five Years	6.02%	4.70%
After Five Through Ten Years	5.32%	5.55%
After Ten Years	3.45%	2.84%
Total	3.97%	3.68%
Municipals
Amortized cost
Less Than One Year		$ 275
After One Through Five Years		0
After Five Through Ten Years		0
After Ten Years		0
Amortized Cost		275
Estimated fair value
Less Than One Year		275
After One Through Five Years		0
After Five Through Ten Years		0
After Ten Years		0
Total		$ 275
Weighted average yield
Less Than One Year		5.61%
After One Through Five Years		0.00%
After Five Through Ten Years		0.00%
After Ten Years		0.00%
Total		5.61%
Equity securities
Amortized cost
Less Than One Year	$ 12,556	$ 9,280
After One Through Five Years	0	0
After Five Through Ten Years	0	0
After Ten Years	0	0
Amortized Cost	12,556	9,280
Estimated fair value
Less Than One Year	12,566	8,947
After One Through Five Years	0	0
After Five Through Ten Years	0	0
After Ten Years	0	0
Total	12,566	8,947
Deposits
Available-for-sale Securities, Other Disclosure Items
Securities pledged as collateral	$ 1,600	$ 3,400

Securities (Details 2)

Securities (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value
Less Than 12 Months	$ 1,015	$ 1,015
12 Months or Longer	6,091	6,146
Total	7,106	7,161
Unrealized Loss
Less Than 12 Months	(6)	(6)
12 Months or Longer	(409)	(354)
Total	(415)	(360)
Comprehensive income	197,076	154,816	$ 144,283
Net after-tax loss	$ (13)	$ 303	$ 571

Loans and Allowance for Credi55

Loans and Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loans and Leases Receivable, Net Reported Amount
Commercial	$ 9,189,811	$ 7,291,545
Mortgage finance	5,308,160	4,497,338
Construction	2,166,208	2,098,706
Real estate	3,794,577	3,462,203
Loans and Leases Receivable, Gross, Consumer, Real Estate	48,684	34,587
Equipment leases	264,903	185,529
Gross loans held for investment	20,772,343	17,569,908
Deferred income (net of direct origination costs)	(97,931)	(71,559)
Allowance for loan losses	(184,655)	(168,126)	$ (141,111)
Loans held for investment, net	$ 20,489,757	$ 17,330,223

Loans and Allowance for Credi56

Loans and Allowance for Credit Losses (Details 1) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Participating mortgage finance loans		$ 171,200	$ 839,000
Interest income recognized on non-accrual loans		1,300	1,400	$ 1,600
Interest lost on non-accrual loans		19,000	7,900	7,000
Non-accrual loans earning on cash basis		0	811
Average impaired loans outstanding		130,777	174,117	$ 102,300
Premium finance loans past due and still accruing		5,500
Nonaccrual loans that met the criteria for restructured		18,800	18,100
Decrease in post-restructuring recorded investment		957	$ 2,000
Loans restructured on non-accrual		$ 7,600
Hurricane | Additional Qualitative Reserve
Financing Receivable, Allowance for Credit Losses [Line Items]
Increase in allowance	$ 4,500
Minimum | Construction loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Term of contracts		1 year
Minimum | Real estate loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Term of contracts		5 years
Maximum | Construction loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Term of contracts		3 years
Maximum | Real estate loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Term of contracts		7 years

Loans and Allowance for Credi57

Loans and Allowance for Credit Losses (Details 2) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Commercial	$ 9,189,811	$ 7,291,545
Mortgage finance	5,308,160	4,497,338
Construction	2,166,208	2,098,706
Real estate	3,794,577	3,462,203
Consumer	48,684	34,587
Equipment leases	264,903	185,529
Total	20,772,343	17,569,908
Pass
Financing Receivable, Recorded Investment [Line Items]
Commercial	8,967,471	6,941,310
Mortgage finance	5,308,160	4,497,338
Construction	2,152,654	2,074,859
Real estate	3,706,541	3,430,346
Consumer	48,591	34,249
Equipment leases	249,865	181,914
Total	20,433,282	17,160,016
Special mention
Financing Receivable, Recorded Investment [Line Items]
Commercial	19,958	69,447
Mortgage finance	0	0
Construction	13,554	10,901
Real estate	53,652	21,932
Consumer	0	0
Equipment leases	495	3,532
Total	87,659	105,812
Substandard- accruing
Financing Receivable, Recorded Investment [Line Items]
Commercial	102,651	115,848
Mortgage finance	0	0
Construction	0	12,787
Real estate	32,671	7,516
Consumer	93	138
Equipment leases	14,543	0
Total	149,958	136,289
Non-accrual
Financing Receivable, Recorded Investment [Line Items]
Commercial	99,731	164,940
Mortgage finance	0	0
Construction	0	159
Real estate	1,713	2,409
Consumer	0	200
Equipment leases	0	83
Total	$ 101,444	$ 167,791

Loans and Allowance for Credi58

Loans and Allowance for Credit Losses (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 168,126	$ 141,111
Provision for loan losses	46,351	74,589
Charge-offs	34,674	57,133
Recoveries	4,852	9,559
Net charge-offs (recoveries)	29,822	47,574
Ending balance	184,655	168,126
Period end amount allocated to:
Loans individually evaluated for impairment	24,417	34,605
Loans collectively evaluated for impairment	160,238	133,521
Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	128,768	112,446
Provision for loan losses	19,590	63,516
Charge-offs	34,145	56,558
Recoveries	4,593	9,364
Net charge-offs (recoveries)	29,552	47,194
Ending balance	118,806	128,768
Period end amount allocated to:
Loans individually evaluated for impairment	24,316	34,405
Loans collectively evaluated for impairment	94,490	94,363
Mortgage Finance
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0	0
Provision for loan losses	0	0
Charge-offs	0	0
Recoveries	0	0
Net charge-offs (recoveries)	0	0
Ending balance	0	0
Period end amount allocated to:
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	0	0
Construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	13,144	6,836
Provision for loan losses	6,084	6,274
Charge-offs	59	0
Recoveries	104	34
Net charge-offs (recoveries)	(45)	(34)
Ending balance	19,273	13,144
Period end amount allocated to:
Loans individually evaluated for impairment	0	24
Loans collectively evaluated for impairment	19,273	13,120
Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	19,149	13,381
Provision for loan losses	15,353	6,233
Charge-offs	290	528
Recoveries	75	63
Net charge-offs (recoveries)	215	465
Ending balance	34,287	19,149
Period end amount allocated to:
Loans individually evaluated for impairment	101	133
Loans collectively evaluated for impairment	34,186	19,016
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	241	338
Provision for loan losses	226	(71)
Charge-offs	180	47
Recoveries	70	21
Net charge-offs (recoveries)	110	26
Ending balance	357	241
Period end amount allocated to:
Loans individually evaluated for impairment	0	30
Loans collectively evaluated for impairment	357	211
Equipment Leases
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,124	3,931
Provision for loan losses	2,408	(2,884)
Charge-offs	0	0
Recoveries	10	77
Net charge-offs (recoveries)	(10)	(77)
Ending balance	3,542	1,124
Period end amount allocated to:
Loans individually evaluated for impairment	0	13
Loans collectively evaluated for impairment	3,542	1,111
Additional Qualitative Reserve
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	5,700	4,179
Provision for loan losses	2,690	1,521
Charge-offs	0	0
Recoveries	0	0
Net charge-offs (recoveries)	0	0
Ending balance	8,390	5,700
Period end amount allocated to:
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	$ 8,390	$ 5,700

Loans and Allowance for Credi59

Loans and Allowance for Credit Losses Loans and Allowance for Credit Losses (Details 4) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	$ 2,000	$ 20,000	$ 13,000	$ 9,000	$ 9,000	$ 22,000	$ 16,000	$ 30,000	$ 44,000	$ 77,000	$ 53,250
Unfunded loan commitments
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses, beginning balance				$ 11,422				$ 9,011	11,422	9,011
Beginning balance									(2,351)	2,411
Allowance for credit losses, ending balance	$ 9,071				$ 11,422				$ 9,071	$ 11,422	$ 9,011

Loans and Allowance for Credi60

Loans and Allowance for Credit Losses (Details 5) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans individually evaluated for impairment	$ 102,684	$ 170,862
Loans collectively evaluated for impairment	20,669,659	17,399,046
Gross loans held for investment	20,772,343	17,569,908
Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans individually evaluated for impairment	100,676	166,669
Loans collectively evaluated for impairment	9,089,135	7,124,876
Gross loans held for investment	9,189,811	7,291,545
Mortgage Finance
Financing Receivable, Recorded Investment [Line Items]
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	5,308,160	4,497,338
Gross loans held for investment	5,308,160	4,497,338
Construction
Financing Receivable, Recorded Investment [Line Items]
Loans individually evaluated for impairment	0	159
Loans collectively evaluated for impairment	2,166,208	2,098,547
Gross loans held for investment	2,166,208	2,098,706
Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans individually evaluated for impairment	2,008	3,751
Loans collectively evaluated for impairment	3,792,569	3,458,452
Gross loans held for investment	3,794,577	3,462,203
Consumer
Financing Receivable, Recorded Investment [Line Items]
Loans individually evaluated for impairment	0	200
Loans collectively evaluated for impairment	48,684	34,387
Gross loans held for investment	48,684	34,587
Equipment Leases
Financing Receivable, Recorded Investment [Line Items]
Loans individually evaluated for impairment	0	83
Loans collectively evaluated for impairment	264,903	185,446
Gross loans held for investment	$ 264,903	$ 185,529

Loans and Allowance for Credi61

Loans and Allowance for Credit Losses (Details 6) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Recorded Investment
With No Related Allowanced Recorded, Recorded Investment	$ 39,357	$ 72,704
With An Allowanced Recorded, Recorded Investment	63,327	98,158
Combined, Recorded Investment	102,684	170,862
Unpaid Principal Balance
With No Related Allowanced Recorded, Unpaid Principal Balance	41,955	84,597
With An Allowanced Recorded, Unpaid Principal Balance	75,807	112,400
Combined, Unpaid Principal Balance	117,762	196,997
Related Allowance	24,417	34,605
Average Recorded Investment
With No Related Allowanced Recorded, Average Recorded Investment	61,709	74,100
With An Allowanced Recorded, Average Recorded Investment	69,068	100,017
Combined, Average Recorded Investment	130,777	174,117	$ 102,300
Interest Income Recognized
With No Related Allowanced Recorded, Interest Income Recognized	0	38
With An Allowanced Recorded, Interest Income Recognized	6	24
Combined, Interest Income Recognized	6	62
Commercial | Business loans
Recorded Investment
With No Related Allowanced Recorded, Recorded Investment	16,835	23,868
With An Allowanced Recorded, Recorded Investment	18,645	21,303
Combined, Recorded Investment	35,480	45,171
Unpaid Principal Balance
With No Related Allowanced Recorded, Unpaid Principal Balance	18,257	27,992
With An Allowanced Recorded, Unpaid Principal Balance	19,020	21,303
Combined, Unpaid Principal Balance	37,277	49,295
Related Allowance	2,544	7,055
Average Recorded Investment
With No Related Allowanced Recorded, Average Recorded Investment	22,964	12,361
With An Allowanced Recorded, Average Recorded Investment	16,960	22,277
Combined, Average Recorded Investment	39,924	34,638
Interest Income Recognized
With No Related Allowanced Recorded, Interest Income Recognized	0	0
With An Allowanced Recorded, Interest Income Recognized	0	0
Combined, Interest Income Recognized	0	0
Commercial | Energy loans
Recorded Investment
With No Related Allowanced Recorded, Recorded Investment	21,426	46,753
With An Allowanced Recorded, Recorded Investment	43,770	74,745
Combined, Recorded Investment	65,196	121,498
Unpaid Principal Balance
With No Related Allowanced Recorded, Unpaid Principal Balance	22,602	54,522
With An Allowanced Recorded, Unpaid Principal Balance	55,875	88,987
Combined, Unpaid Principal Balance	78,477	143,509
Related Allowance	21,772	27,350
Average Recorded Investment
With No Related Allowanced Recorded, Average Recorded Investment	36,579	54,075
With An Allowanced Recorded, Average Recorded Investment	50,867	73,637
Combined, Average Recorded Investment	87,446	127,712
Interest Income Recognized
With No Related Allowanced Recorded, Interest Income Recognized	0	0
With An Allowanced Recorded, Interest Income Recognized	6	24
Combined, Interest Income Recognized	6	24
Construction | Market risk
Recorded Investment
With No Related Allowanced Recorded, Recorded Investment	0	0
With An Allowanced Recorded, Recorded Investment	0	159
Combined, Recorded Investment	0	159
Unpaid Principal Balance
With No Related Allowanced Recorded, Unpaid Principal Balance	0	0
With An Allowanced Recorded, Unpaid Principal Balance	0	159
Combined, Unpaid Principal Balance	0	159
Related Allowance	0	24
Average Recorded Investment
With No Related Allowanced Recorded, Average Recorded Investment	0	2,778
With An Allowanced Recorded, Average Recorded Investment	27	53
Combined, Average Recorded Investment	27	2,831
Interest Income Recognized
With No Related Allowanced Recorded, Interest Income Recognized	0	0
With An Allowanced Recorded, Interest Income Recognized	0	0
Combined, Interest Income Recognized	0	0
Real estate | Market risk
Recorded Investment
With No Related Allowanced Recorded, Recorded Investment	0	0
With An Allowanced Recorded, Recorded Investment	295	1,342
Combined, Recorded Investment	295	1,342
Unpaid Principal Balance
With No Related Allowanced Recorded, Unpaid Principal Balance	0	0
With An Allowanced Recorded, Unpaid Principal Balance	295	1,342
Combined, Unpaid Principal Balance	295	1,342
Related Allowance	6	20
Average Recorded Investment
With No Related Allowanced Recorded, Average Recorded Investment	0	0
With An Allowanced Recorded, Average Recorded Investment	485	3,000
Combined, Average Recorded Investment	485	3,000
Interest Income Recognized
With No Related Allowanced Recorded, Interest Income Recognized	0	0
With An Allowanced Recorded, Interest Income Recognized	0	0
Combined, Interest Income Recognized	0	0
Real estate | Commercial
Recorded Investment
With No Related Allowanced Recorded, Recorded Investment	1,096	2,083
With An Allowanced Recorded, Recorded Investment	499	0
Combined, Recorded Investment	1,595	2,083
Unpaid Principal Balance
With No Related Allowanced Recorded, Unpaid Principal Balance	1,096	2,083
With An Allowanced Recorded, Unpaid Principal Balance	499	0
Combined, Unpaid Principal Balance	1,595	2,083
Related Allowance	75	0
Average Recorded Investment
With No Related Allowanced Recorded, Average Recorded Investment	2,166	4,483
With An Allowanced Recorded, Average Recorded Investment	166	0
Combined, Average Recorded Investment	2,332	4,483
Interest Income Recognized
With No Related Allowanced Recorded, Interest Income Recognized	0	38
With An Allowanced Recorded, Interest Income Recognized	0	0
Combined, Interest Income Recognized	0	38
Real estate | Secured by 1-4 family
Recorded Investment
With No Related Allowanced Recorded, Recorded Investment	0	0
With An Allowanced Recorded, Recorded Investment	118	326
Combined, Recorded Investment	118	326
Unpaid Principal Balance
With No Related Allowanced Recorded, Unpaid Principal Balance	0	0
With An Allowanced Recorded, Unpaid Principal Balance	118	326
Combined, Unpaid Principal Balance	118	326
Related Allowance	20	113
Average Recorded Investment
With No Related Allowanced Recorded, Average Recorded Investment	0	0
With An Allowanced Recorded, Average Recorded Investment	516	435
Combined, Average Recorded Investment	516	435
Interest Income Recognized
With No Related Allowanced Recorded, Interest Income Recognized	0	0
With An Allowanced Recorded, Interest Income Recognized	0	0
Combined, Interest Income Recognized	0	0
Consumer
Recorded Investment
With No Related Allowanced Recorded, Recorded Investment	0	0
With An Allowanced Recorded, Recorded Investment	0	200
Combined, Recorded Investment	0	200
Unpaid Principal Balance
With No Related Allowanced Recorded, Unpaid Principal Balance	0	0
With An Allowanced Recorded, Unpaid Principal Balance	0	200
Combined, Unpaid Principal Balance	0	200
Related Allowance	0	30
Average Recorded Investment
With No Related Allowanced Recorded, Average Recorded Investment	0	0
With An Allowanced Recorded, Average Recorded Investment	33	67
Combined, Average Recorded Investment	33	67
Interest Income Recognized
With No Related Allowanced Recorded, Interest Income Recognized	0	0
With An Allowanced Recorded, Interest Income Recognized	0	0
Combined, Interest Income Recognized	0	0
Equipment leases
Recorded Investment
With No Related Allowanced Recorded, Recorded Investment	0	0
With An Allowanced Recorded, Recorded Investment	0	83
Combined, Recorded Investment	0	83
Unpaid Principal Balance
With No Related Allowanced Recorded, Unpaid Principal Balance	0	0
With An Allowanced Recorded, Unpaid Principal Balance	0	83
Combined, Unpaid Principal Balance	0	83
Related Allowance	0	13
Average Recorded Investment
With No Related Allowanced Recorded, Average Recorded Investment	0	403
With An Allowanced Recorded, Average Recorded Investment	14	548
Combined, Average Recorded Investment	14	951
Interest Income Recognized
With No Related Allowanced Recorded, Interest Income Recognized	0	0
With An Allowanced Recorded, Interest Income Recognized	0	0
Combined, Interest Income Recognized	$ 0	$ 0

Loans and Allowance for Credi62

Loans and Allowance for Credit Losses (Details 7) $ in Thousands	Dec. 31, 2017USD ($)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 39,936
Non-accrual	101,444
Current	20,630,963
Total	20,772,343
Commercial | Business loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	32,359
Non-accrual	34,535
Current	7,992,918
Total	8,059,812
Commercial | Energy loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,100
Non-accrual	65,196
Current	1,063,703
Total	1,129,999
Mortgage Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Non-accrual	0
Current	5,308,160
Total	5,308,160
Construction | Market risk
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	239
Non-accrual	0
Current	2,098,446
Total	2,098,685
Construction | Secured by 1-4 family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,635
Non-accrual	0
Current	30,102
Total	31,737
Real estate | Market risk
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,019
Non-accrual	0
Current	2,681,527
Total	2,683,546
Real estate | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Non-accrual	1,595
Current	839,787
Total	841,382
Real estate | Secured by 1-4 family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,705
Non-accrual	118
Current	267,826
Total	269,649
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	174
Non-accrual	0
Current	48,510
Total	48,684
Equipment leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	705
Non-accrual	0
Current	264,198
Total	264,903
30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	17,954
30 to 59 Days Past Due | Commercial | Business loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	12,346
30 to 59 Days Past Due | Commercial | Energy loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,100
30 to 59 Days Past Due | Mortgage Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
30 to 59 Days Past Due | Construction | Market risk
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	239
30 to 59 Days Past Due | Construction | Secured by 1-4 family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,635
30 to 59 Days Past Due | Real estate | Market risk
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,724
30 to 59 Days Past Due | Real estate | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
30 to 59 Days Past Due | Real estate | Secured by 1-4 family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	174
30 to 59 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	100
30 to 59 Days Past Due | Equipment leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	636
60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	13,553
60 to 89 Days Past Due | Commercial | Business loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	13,029
60 to 89 Days Past Due | Commercial | Energy loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
60 to 89 Days Past Due | Mortgage Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
60 to 89 Days Past Due | Construction | Market risk
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
60 to 89 Days Past Due | Construction | Secured by 1-4 family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
60 to 89 Days Past Due | Real estate | Market risk
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	295
60 to 89 Days Past Due | Real estate | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
60 to 89 Days Past Due | Real estate | Secured by 1-4 family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	139
60 to 89 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	74
60 to 89 Days Past Due | Equipment leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	16
Greater Than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	8,429
Greater Than 90 Days | Commercial | Business loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,984
Greater Than 90 Days | Commercial | Energy loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Greater Than 90 Days | Mortgage Finance
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Greater Than 90 Days | Construction | Market risk
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Greater Than 90 Days | Construction | Secured by 1-4 family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Greater Than 90 Days | Real estate | Market risk
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Greater Than 90 Days | Real estate | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Greater Than 90 Days | Real estate | Secured by 1-4 family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,392
Greater Than 90 Days | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Greater Than 90 Days | Equipment leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 53

Loans and Allowance for Credi63

Loans and Allowance for Credit Losses (Details 8) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)contract	Dec. 31, 2016USD ($)contract
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	4	2
Pre-Restructuring Outstanding Recorded Investment	$ 8,597	$ 14,235
Post-Restructuring Outstanding Recorded Investment	$ 7,640	$ 12,236
Energy [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1
Pre-Restructuring Outstanding Recorded Investment	$ 1,070
Post-Restructuring Outstanding Recorded Investment	$ 0
Commercial
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	3	2
Pre-Restructuring Outstanding Recorded Investment	$ 7,527	$ 14,235
Post-Restructuring Outstanding Recorded Investment	$ 7,640	$ 12,236

Loans and Allowance for Credi64

Loans and Allowance for Credit Losses (Details 9) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Modifications [Line Items]
Loans modified as restructured loans	$ 7,640	$ 12,236
Extended maturity
Financing Receivable, Modifications [Line Items]
Loans modified as restructured loans	712	0
Adjusted payment schedule
Financing Receivable, Modifications [Line Items]
Loans modified as restructured loans	6,928	0
Combination of maturity extension and payment schedule adjustment
Financing Receivable, Modifications [Line Items]
Loans modified as restructured loans	$ 0	$ 12,236

OREO and Valuation Allowance 65

OREO and Valuation Allowance for Losses on OREO (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Real Estate [Roll Forward]
Beginning balance	$ 18,961	$ 278	$ 568
Additions	0	18,822	1,267
Sales	(1,108)	(139)	(1,557)
Valuation allowance for OREO	0	0	0
Direct write-downs	(6,111)	0	0
Ending balance	11,742	18,961	278
OREO write-down	$ 6,111	$ 0	$ 0

Certain Transfers of Financia66

Certain Transfers of Financial Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans and Leases Receivable Disclosure [Line Items]
Outstanding balance	$ 1,009,271	$ 980,414
Fair value	1,007,695	968,929
Fair value over (under) outstanding balance	(1,576)	$ (11,485)
SBA loans | Held for sale
Loans and Leases Receivable Disclosure [Line Items]
Fair value over (under) outstanding balance	$ 3,300

Certain Transfers of Financia67

Certain Transfers of Financial Assets Certain Transfers of Financial Assets (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Loans Receivable Held-for-sale, Net, Reconciliation to Cash Flow [Roll Forward]
Loans held for sale, beginning balance	$ 968,929	$ 86,075
Loans purchased	5,556,964	3,327,482
Payments and loans sold	(5,524,798)	(2,433,348)
Change in fair value	9,909	(11,280)
Loans held for sale, ending balance	$ 1,011,004	$ 968,929

Certain Transfers of Financia68

Certain Transfers of Financial Assets (Details 2) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Valuation Allowance for Impairment of Recognized Servicing Assets, Sales and Disposals [Abstract]
Valuation allowance, beginning balance	$ 835,000
Valuation allowance, ending balance	1,333,000	$ 835,000
Mortgage Servicing Rights
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance, beginning of year	28,536,000	423,000
Capitalized servicing rights	67,970,000	29,816,000
Amortization	(8,356,000)	(1,703,000)
Balance, end of period	88,150,000	28,536,000
Valuation Allowance for Impairment of Recognized Servicing Assets, Sales and Disposals [Abstract]
Valuation allowance, beginning balance	0	0
Increase in valuation allowance	2,823,000	0
Valuation allowance, ending balance	2,823,000	0
MSRs, net	85,327,000	28,536,000
Fair value	$ 86,321,000	$ 30,877,000

Certain Transfers of Financia69

Certain Transfers of Financial Assets (Details 3) - Mortgage Servicing Rights	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities [Line Items]
Average discount rates (percent)	9.90%	9.96%
Expected prepayment speeds (percent)	9.99%	7.91%
Weighted-average life, in years	7 years	8 years

Certain Transfers of Financia70

Certain Transfers of Financial Assets (Details 4) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Transfers and Servicing [Abstract]
Principal amount outstanding of loans in servicing portfolio	$ 7,000,000,000	$ 2,200,000,000
Escrow deposits related to servicing portfolio	73,400,000	21,000,000
Estimated exposure related to servicing assets	1,333,000	835,000
Losses due to repurchase indemnification and make-whole obligations	31,000	0
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due balance	39,936,000
Held for sale | 90 days or more past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due balance	19,700,000	$ 0
Government guarantees | Held for sale | 90 days or more past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due balance	19,000,000
Mortgage servicing rights
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impairment charges	$ 2,800,000

Certain Transfers of Financia71

Certain Transfers of Financial Assets Certain Transfers of Financial Assets (Details 5) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Transfers and Servicing [Abstract]
50 bp adverse change in prepayment speed	$ (11,896)	$ (2,833)
100 bp adverse change in prepayment speed	$ (28,226)	$ (6,812)

Goodwill and Other Intangible72

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Goodwill
Gross	$ 15,468	$ 15,468
Accumulated Amortization	(374)	(374)
Net	15,094	15,094
Intangible assets—customer relationships and trademarks
Gross	9,006	9,006
Accumulated Amortization	(5,060)	(4,588)
Net	3,946	4,418
Total goodwill and intangible assets
Gross	24,474	24,474
Accumulated Amortization	(5,434)	(4,962)
Net	$ 19,040	$ 19,512

Goodwill and Other Intangible73

Goodwill and Other Intangible Assets (Details 1) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
2,016	$ 470
2,017	470
2,018	432
2,019	405
2,020	405
Thereafter	1,764
Net	$ 3,946	$ 4,418

Goodwill and Other Intangible74

Goodwill and Other Intangible Assets (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Total intangible assets	$ 19,040	$ 19,512
Amortization expense related to intangible assets	$ 472	$ 448	$ 628

Premises and Equipment (Details

Premises and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of premises and equipment
Premises and equipment, gross	$ 58,024	$ 47,046
Accumulated depreciation	(32,848)	(27,271)
Total premises and equipment, net	25,176	19,775
Depreciation, Depletion and Amortization
Depreciation expense	6,900	6,000	$ 4,600
Premises
Summary of premises and equipment
Premises and equipment, gross	25,790	22,887
Furniture and equipment
Summary of premises and equipment
Premises and equipment, gross	$ 32,234	$ 24,159

Deposits (Details)

Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Non-interest bearing deposits
Non-interest-bearing demand deposits	$ 7,812,660	$ 7,994,201
Interest-bearing deposits
Transaction	2,567,208	1,954,834
Savings	8,214,059	6,625,177
Time	529,253	442,619
Total interest-bearing deposits	11,310,520	9,022,630
Total deposits	$ 19,123,180	$ 17,016,831

Deposits (Details 1)

Deposits (Details 1) $ in Thousands	Dec. 31, 2017USD ($)
Scheduled maturities of interest bearing time deposits
2,015	$ 492,208
2,016	33,289
2,017	2,817
2,018	246
2,019	244
2023 and after	449
Interest bearing time deposits, total	$ 529,253

Deposits (Details 2)

Deposits (Details 2) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deposits [Abstract]
Deposits from related parties	$ 13.5	$ 15.4
Interest-bearing time deposits of $250,000 or more	$ 300.5	$ 225.5

Borrowing Arrangements (Details

Borrowing Arrangements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Borrowings	$ 3,559,852	$ 2,504,025	$ 2,037,139
Maximum outstanding at any month end	3,559,852	2,511,579	2,042,457
Federal funds purchased
Debt Instrument [Line Items]
Federal funds purchased	$ 359,338	$ 101,800	$ 74,164
Interest rate	1.45%	0.80%	0.55%
Weighted-average interest rate	1.20%	0.57%	0.29%
Average balance for the year	$ 215,900	$ 90,900	$ 98,800
Customer repurchase agreements
Debt Instrument [Line Items]
Customer repurchase agreements	$ 5,702	$ 7,775	$ 68,887
Interest rate	0.03%	0.05%	0.02%
Customer repurchase agreements | Collaterized securities
Debt Instrument [Line Items]
Borrowings	$ 7,300	$ 10,200	$ 14,200
FHLB borrowings
Debt Instrument [Line Items]
Borrowings	$ 2,800,000	$ 2,000,000	$ 1,500,000
Interest rate	1.35%	0.61%	0.31%
Weighted-average interest rate	1.08%	0.43%	0.18%
Average balance for the year	$ 1,400,000	$ 1,367,270	$ 1,243,280
Subordinated notes
Debt Instrument [Line Items]
Borrowings	$ 281,406	$ 281,044	$ 280,682
Interest rate	5.86%	5.87%	5.75%
Trust preferred subordinated debentures
Debt Instrument [Line Items]
Borrowings	$ 113,406	$ 113,406	$ 113,406
Interest rate	3.55%	2.90%	2.47%

Borrowing Arrangements (Detai80

Borrowing Arrangements (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of other borrowing capacities
Total FHLB borrowing capacity	$ 3,893,066	$ 3,059,568	$ 4,102,609
Unused Federal funds lines available from commercial banks	885,000	1,118,000	1,231,000
Unused Federal Reserve Borrowings capacity	4,114,594	3,179,087	2,966,702
Average amount oustanding	6,800
FHLB borrowing capacity relating to loans
Summary of other borrowing capacities
Total FHLB borrowing capacity	3,890,995	3,057,915	4,101,396
Unused Federal funds lines available from commercial banks		130,000
FHLB borrowing capacity relating to securities
Summary of other borrowing capacities
Total FHLB borrowing capacity	$ 2,071	$ 1,653	$ 1,213

Borrowing Arrangements (Detai81

Borrowing Arrangements (Details 2) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Federal funds purchased and repurchase agreements	$ 365,040	$ 109,575
Within One Year	3,165,040
After One But Within Three Years	0
After Three But Within Five Years	0
After Five Years	394,812
Total	3,559,852	2,504,025	$ 2,037,139
FHLB borrowings
Debt Instrument [Line Items]
Within One Year	2,800,000
After One But Within Three Years	0
After Three But Within Five Years	0
After Five Years	0
Total	2,800,000
Subordinated notes
Debt Instrument [Line Items]
Within One Year	0
After One But Within Three Years	0
After Three But Within Five Years	0
After Five Years	281,406
Total	281,406	281,044	280,682
Trust preferred subordinated debentures
Debt Instrument [Line Items]
Within One Year	0
After One But Within Three Years	0
After Three But Within Five Years	0
After Five Years	113,406
Total	$ 113,406	$ 113,406	$ 113,406

Long-Term Debt (Details)

Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 31, 2014	Sep. 21, 2012
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Total borrowings	$ 3,559,852	$ 2,504,025	$ 2,037,139
Trust preferred securities issued	113,406	$ 113,406		$ 175,000	$ 111,000
Stated interest rate				5.25%	6.50%
Trust preferred subordinated debentures
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Total borrowings	$ 113,400

Long-Term Debt (Details 1)

Long-Term Debt (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jan. 31, 2014	Sep. 21, 2012
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Trust preferred securities issued	$ 113,406	$ 113,406	$ 175,000	$ 111,000
Texas Capital Bancshares Statutory Trust I
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Date issued	Nov. 19, 2002
Trust preferred securities issued	$ 10,310
Floating or fixed rate securities	Floating
Maturity date	Nov. 30, 2032
Texas Capital Bancshares Statutory Trust I | LIBOR
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Interest rate on subordinated debentures	3 month LIBOR + 3.35%
Interest rate on subordinated debentures, spread on variable rate	3.35%
Texas Capital Statutory Trust II
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Date issued	Apr. 10, 2003
Trust preferred securities issued	$ 10,310
Floating or fixed rate securities	Floating
Maturity date	Apr. 30, 2033
Texas Capital Statutory Trust II | LIBOR
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Interest rate on subordinated debentures	3 month LIBOR + 3.25%
Interest rate on subordinated debentures, spread on variable rate	3.25%
Texas Capital Statutory Trust III
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Date issued	Oct. 6, 2005
Trust preferred securities issued	$ 25,774
Floating or fixed rate securities	Floating
Maturity date	Dec. 31, 2035
Texas Capital Statutory Trust III | LIBOR
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Interest rate on subordinated debentures	3 month LIBOR + 1.51%
Interest rate on subordinated debentures, spread on variable rate	1.51%
Texas Capital Statutory Trust IV
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Date issued	Apr. 28, 2006
Trust preferred securities issued	$ 25,774
Floating or fixed rate securities	Floating
Maturity date	Jun. 30, 2036
Texas Capital Statutory Trust IV | LIBOR
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Interest rate on subordinated debentures	3 month LIBOR + 1.60%
Interest rate on subordinated debentures, spread on variable rate	1.60%
Texas Capital Statutory Trust V
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Date issued	Sep. 29, 2006
Trust preferred securities issued	$ 41,238
Floating or fixed rate securities	Floating
Maturity date	Dec. 31, 2036
Texas Capital Statutory Trust V | LIBOR
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Interest rate on subordinated debentures	3 month LIBOR + 1.71%
Interest rate on subordinated debentures, spread on variable rate	1.71%

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Tax impact of TCJA									$ 17,600
Gross deferred tax asset	$ 63,000				$ 89,700				63,000	$ 89,700
Current:
Federal									94,112	86,612	$ 80,957
State									3,257	2,412	2,245
Total									97,369	89,024	83,202
Deferred
Federal									31,276	(2,946)	(3,561)
State									0	0	0
Total									31,276	(2,946)	(3,561)
Total expense
Federal									125,388	83,666	77,396
State									3,257	2,412	2,245
Total	$ 50,143	$ 29,850	$ 25,819	$ 22,833	$ 26,149	$ 23,931	$ 21,866	$ 14,132	$ 128,645	$ 86,078	$ 79,641

Income Taxes (Details 1)

Income Taxes (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Allowance for credit losses	$ 42,213	$ 64,009
Loan origination fees	10,084	13,536
Stock compensation	4,460	5,761
Non-accrual interest	1,680	2,537
Deferred lease expense	911	1,519
Other	3,686	2,322
Total deferred tax assets	63,034	89,684
Deferred tax liabilities:
Loan origination costs	(1,304)	(1,722)
Leases	(6,850)	(7,962)
MSRs	(17,619)	(10,973)
Depreciation	(7,354)	(6,941)
Unrealized gain on securities	(138)	(223)
Other	(2,068)	(2,971)
Total deferred tax liabilities	(35,333)	(30,792)
Net deferred tax asset	$ 27,701	$ 58,892
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Tax at U.S. statutory rate	35.00%	35.00%	35.00%
State taxes (percent)	1.00%	1.00%	1.00%
Non-deductible expenses (percent)	1.00%	1.00%	1.00%
Deductible tax asset write-off (percent)	5.00%	0.00%	0.00%
Non-taxable income (percent)	(1.00%)	(1.00%)	(1.00%)
Other (percent)	(1.00%)	(0.00%)	(1.00%)
Total (percent)	40.00%	36.00%	35.00%

Stock-Based Compensation and 86

Stock-Based Compensation and Employee Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer contribution	$ 8,400,000	$ 6,800,000	$ 6,300,000
Eligible employee contribution, minimum (in percent)	1.00%
Eligible employee contribution, maximum (in percent)	10.00%
Number of shares authorized under the plan	2,550,000
Number of shares available to be issued under the plan	2,169,324
Compensation expense	$ 7,790,000
Compensation cost for all share-based arrangements, net of taxes	5,300,000	3,300,000	$ 3,000,000
Employer discretionary contributions	$ 260,000	$ 0
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	121,243	213,577	145,952
Compensation expense		$ 4,771,000	$ 4,230,000
Weighted average remaining contractual life of SARs currently outstanding (in years)	8 years 4 months	8 years 7 months 24 days	8 years 3 months 15 days
Weighted average period over which unrecognized compensation expense is expected to be recognized (in years)	3 years 1 month 25 days	3 years 4 months 15 days	3 years 3 months 20 days
SARs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0	0	0
Compensation expense	$ 265,000	$ 307,000	$ 367,000
Weighted average remaining contractual life of SARs currently outstanding (in years)	3 years 4 months 5 days	4 years 3 months 24 days	3 years 28 days
Weighted average period over which unrecognized compensation expense is expected to be recognized (in years)	9 months	1 year 6 months 7 days	2 years 4 months 25 days
Cash based performance
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of cash-based performance units issued in period	121,260	224,071	146,153
Number of cash-based performance units outstanding	390,350
Cash-based compensation expense	$ 13,900,000	$ 8,500,000	$ 7,700,000
Cash-based compensation expense, net of taxes	$ 9,100,000	$ 5,500,000	$ 5,000,000
Service based
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	4 years
Service and performance
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average remaining contractual life of SARs currently outstanding (in years)	7 years 11 months 18 days
Minimum | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	4 years	4 years	4 years
Maximum | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	5 years	5 years	5 years
Director | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			0
2006 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized under the plan	400,000
Number of shares purchased under the plan	132,285	124,572	113,910

Stock-Based Compensation and 87

Stock-Based Compensation and Employee Benefits (Details 3) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Additional Information:
Compensation expense	$ 7,790,000
Unrecognized compensation expense	$ 18,730,000
SARs
SARs
RSUs outstanding at beginning of year	125,863	360,544	445,009
Granted	0	0	0
SARs exercised	(51,500)	(234,681)	(84,465)
SARs forfeited	0	0	0
RSUs outstanding at year-end	74,363	125,863	360,544
Weighted Average Exercise Price
SARs outstanding at beginning of year, weighted average exercise price	$ 31.68	$ 25.73	$ 24.83
SARs granted, weighted average exercise price	0	0	0
SARs exercised, weighted average exercise price	33.94	22.54	20.97
SARs forfeited, weighted average exercise price	0	0	0
SARs outstanding at year end, weighted average exercise price	$ 30.12	$ 31.68	$ 25.73
Additional Information:
SARs vested and exercisable at year-end	60,463	94,463	307,144
SARs vested and exercisable at year end, weighted average exercise price	$ 26.02	$ 26.73	$ 22.49
Weighted average remaining contractual life of SARs vested	2 years 9 months 27 days	3 years 7 months 12 days	2 years 4 months 8 days
Compensation expense	$ 265,000	$ 307,000	$ 367,000
Unrecognized compensation expense	$ 127,000	$ 392,000	$ 699,000
Weighted average period over which unrecognized compensation expense is expected to be recognized (in years)	9 months	1 year 6 months 7 days	2 years 4 months 25 days
Fair value of shares vested during the year	$ 294,000	$ 337,000	$ 436,000
Weighted average remaining contractual life of SARs currently outstanding (in years)	3 years 4 months 5 days	4 years 3 months 24 days	3 years 28 days
Intrinsic value of SARs exercised	$ 3,802,000	$ 4,881,000	$ 8,291,000

Stock-Based Compensation and 88

Stock-Based Compensation and Employee Benefits (Details 4) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Weighted- Average Grant- Date Fair Value
Compensation expense	$ 7,790,000
Unrecognized compensation expense	$ 18,730,000
RSUs
Number of Shares
RSUs outstanding at beginning of year	425,055	333,174	295,165
Granted	121,243	213,577	145,952
RSUs exercised	(102,057)	(94,296)	(95,743)
SARs forfeited	(20,509)	(27,400)	(12,200)
RSUs outstanding at year-end	423,732	425,055	333,174
Weighted- Average Grant- Date Fair Value
Balance at beginning of year, weighted average grant-date fair value	$ 51.28	$ 48.60	$ 42.93
Granted, weighted average grant-date fair value	80.40	51.75	51.96
RSUs exercised	48.93	42.87	38.05
Forfeited, weighted average grant-date fair value	54.75	51.18	43.89
Balance at year end, weighted average grant-date fair value	$ 60.01	$ 51.28	$ 48.60
Compensation expense		$ 4,771,000	$ 4,230,000
Unrecognized compensation expense		$ 17,167,000	$ 13,038,000
Weighted average period over which unrecognized compensation expense is expected to be recognized (in years)	3 years 1 month 25 days	3 years 4 months 15 days	3 years 3 months 20 days
Weighted average remaining contractual life of RSUs currently outstanding	8 years 4 months	8 years 7 months 24 days	8 years 3 months 15 days
RSAs
Number of Shares
RSUs outstanding at beginning of year	1,472	0
Granted	641	1,472
SARs forfeited	(491)	0
RSUs outstanding at year-end	1,622	1,472	0
Weighted- Average Grant- Date Fair Value
Balance at beginning of year, weighted average grant-date fair value	$ 33.97	$ 0
Granted, weighted average grant-date fair value	78	33.97
Forfeited, weighted average grant-date fair value	33.97	0
Balance at year end, weighted average grant-date fair value	$ 51.37	$ 33.97	$ 0
Compensation expense	$ 24,000	$ 15,000
Unrecognized compensation expense	$ 61,000	$ 35,000
Weighted average period over which unrecognized compensation expense is expected to be recognized (in years)	2 years 1 month 7 days	2 years 1 month 7 days
Weighted average remaining contractual life of RSUs currently outstanding	8 years 8 months 10 days	9 years 1 month 18 days

Financial Instruments with Of89

Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Allowance allocation for off-balance sheet commitments	$ 9,100	$ 11,400
Commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet liability	6,957,847	5,704,381
Standby letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet liability	$ 230,958	$ 171,266

Regulatory Restrictions (Detail

Regulatory Restrictions (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Regulatory Capital Requirements [Abstract]
Required reserve balance at the Federal Reserve	$ 197,300,000	$ 221,900,000
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Mortgage finance	5,308,160,000	4,497,338,000
Mortgage Finance, Average Balance	4,100,000,000
Common Equity Tier 1 [Abstract]
CET1, actual amount	2,033,830,000	1,841,219,000
Total capital (to risk-weighted assets):
Total capital (to risk weighted assets), actual amount	2,768,153,000	2,561,663,000
Tier 1 capital (to risk-weighted assets):
Tier 1 capital (to risk-weighted assets), actual amount	2,293,016,000	2,101,071,000
Tier 1 capital (to average assets):
Tier 1 capital (to average assets), actual amount	$ 2,293,016,000	$ 2,101,071,000
Risk Based Ratios [Abstract]
CET1, actual ratio	8.45%	8.97%
Total capital (to risk weighted assets), actual ratio	11.50%	12.48%
Tier 1 capital (to risk-weighted assets), actual ratio	9.52%	10.23%
Tier 1 capital (to average assets), actual ratio	9.15%	9.34%
Bank
Common Equity Tier 1 [Abstract]
CET1, actual amount	$ 1,992,152,000	$ 1,735,496,000
CET1 to be well capitalized under prompt corrective action provisions, amount	1,563,929	1,334,244
Total capital (to risk-weighted assets):
Total capital (to risk weighted assets), actual amount	2,567,961,000	2,297,528,000
Total capital (to risk weighted assets) to be well capitalized under prompt corrective action provisions, amount	2,406,044	2,052,683
Tier 1 capital (to risk-weighted assets):
Tier 1 capital (to risk-weighted assets), actual amount	2,151,338,000	1,895,348,000
Tier 1 capital (to risk weighted assets) to be well capitalized under prompt corrective action provisions, amount	1,924,835	1,642,147
Tier 1 capital (to average assets):
Tier 1 capital (to average assets), actual amount	2,151,338,000	1,895,348,000
Tier 1 capital (to average assets) to be well capitalized under prompt corrective action provisions, amount	$ 1,252,680	$ 1,125,087
Risk Based Ratios [Abstract]
CET1, actual ratio	8.28%	8.45%
CET1 to be well capitalized under prompt corrective action provisions, ratio	6.50%	6.50%
Total capital (to risk weighted assets), actual ratio	10.67%	11.19%
Total capital (to risk weighted assets) to be well capitalized under prompt corrective action provisions, ratio	10.00%	10.00%
Tier 1 capital (to risk-weighted assets), actual ratio	8.94%	9.23%
Tier 1 capital (to risk weighted assets) to be well capitalized under prompt corrective action provisions, ratio	8.00%	8.00%
Tier 1 capital (to average assets), actual ratio	8.59%	8.42%
Tier 1 capital (to average assets) to be well capitalized under prompt corrective action provisions, ratio	5.00%	5.00%
Basel III, Phase-In Schedule
Common Equity Tier 1 [Abstract]
CET1 for capital adequacy purposes, amount	$ 1,384,448	$ 1,052,205
Total capital (to risk-weighted assets):
Total capital (to risk weighted assets) for capital adequacy purposes, amount	2,227,221	1,770,766
Tier 1 capital (to risk-weighted assets):
Tier 1 capital (to risk-weighted assets) for capital adequacy purposes, amount	1,745,659	1,360,154
Tier 1 capital (to average assets):
Tier 1 capital (to average assets) for capital adequacy purposes, amount	$ 1,002,494	$ 900,268
Risk Based Ratios [Abstract]
CET1 for capital adequacy purposes, ratio	5.75%	5.125%
Total capital (to risk weighted assets) for capital adequacy purposes, ratio	9.25%	8.625%
Tier 1 capital (to risk-weighted assets) for capital adequacy purposes, ratio	7.25%	6.625%
Tier 1 capital (to average assets) for capital adequacy purposes, ratio	4.00%	4.00%
Basel III, Phase-In Schedule | Bank
Common Equity Tier 1 [Abstract]
CET1 for capital adequacy purposes, amount	$ 1,383,475	$ 1,051,989
Total capital (to risk-weighted assets):
Total capital (to risk weighted assets) for capital adequacy purposes, amount	2,225,591	1,770,421
Tier 1 capital (to risk-weighted assets):
Tier 1 capital (to risk-weighted assets) for capital adequacy purposes, amount	1,744,382	1,359,888
Tier 1 capital (to average assets):
Tier 1 capital (to average assets) for capital adequacy purposes, amount	$ 1,002,144	$ 900,070
Risk Based Ratios [Abstract]
CET1 for capital adequacy purposes, ratio	5.75%	5.125%
Total capital (to risk weighted assets) for capital adequacy purposes, ratio	9.25%	8.625%
Tier 1 capital (to risk-weighted assets) for capital adequacy purposes, ratio	7.25%	6.625%
Tier 1 capital (to average assets) for capital adequacy purposes, ratio	4.00%	4.00%
Basel III, Phased-In
Common Equity Tier 1 [Abstract]
CET1 for capital adequacy purposes, amount	$ 1,685,464	$ 1,437,159
Total capital (to risk-weighted assets):
Total capital (to risk weighted assets) for capital adequacy purposes, amount	2,528,196	2,155,715
Tier 1 capital (to risk-weighted assets):
Tier 1 capital (to risk-weighted assets) for capital adequacy purposes, amount	2,046,635	1,745,103
Tier 1 capital (to average assets):
Tier 1 capital (to average assets) for capital adequacy purposes, amount	$ 1,002,494	$ 900,268
Risk Based Ratios [Abstract]
CET1 for capital adequacy purposes, ratio	7.00%	7.00%
Total capital (to risk weighted assets) for capital adequacy purposes, ratio	10.50%	10.50%
Tier 1 capital (to risk-weighted assets) for capital adequacy purposes, ratio	8.50%	8.50%
Tier 1 capital (to average assets) for capital adequacy purposes, ratio	4.00%	4.00%
Basel III, Phased-In | Bank
Common Equity Tier 1 [Abstract]
CET1 for capital adequacy purposes, amount	$ 1,684,000	$ 1,437,000
Total capital (to risk-weighted assets):
Total capital (to risk weighted assets) for capital adequacy purposes, amount	2,526,347	2,155,295
Tier 1 capital (to risk-weighted assets):
Tier 1 capital (to risk-weighted assets) for capital adequacy purposes, amount	2,045,138	1,744,762
Tier 1 capital (to average assets):
Tier 1 capital (to average assets) for capital adequacy purposes, amount	$ 1,002,144	$ 900,070
Risk Based Ratios [Abstract]
CET1 for capital adequacy purposes, ratio	7.00%	7.00%
Total capital (to risk weighted assets) for capital adequacy purposes, ratio	10.50%	10.50%
Tier 1 capital (to risk-weighted assets) for capital adequacy purposes, ratio	8.50%	8.50%
Tier 1 capital (to average assets) for capital adequacy purposes, ratio	4.00%	4.00%

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Net income	$ 44,742	$ 58,684	$ 51,095	$ 42,542	$ 48,386	$ 42,725	$ 38,880	$ 25,128	$ 197,063	$ 155,119	$ 144,854
Preferred stock dividends	2,437	2,438	2,437	2,438	2,437	2,438	2,437	2,438	9,750	9,750	9,750
Net income available to common stockholders	$ 42,305	$ 56,246	$ 48,658	$ 40,104	$ 45,949	$ 40,287	$ 36,443	$ 22,690	$ 187,313	$ 145,369	$ 135,104
Denominator:
Denominator for basic earnings per share—weighted average shares	49,630,000	49,607,000	49,577,000	49,536,000	47,156,000	45,981,000	45,924,000	45,889,000	49,587,169	46,239,210	45,808,440
Effect of employee stock-based awards									239,008	128,228	211,168
Effect of warrants to purchase common stock									433,657	398,464	418,264
Denominator for dilutive earnings per share—adjusted weighted average shares and assumed conversions	50,312,000	50,251,000	50,230,000	50,234,000	47,760,000	46,510,000	46,438,000	46,354,000	50,259,834	46,765,902	46,437,872
Basic earnings per common share	$ 0.85	$ 1.13	$ 0.98	$ 0.81	$ 0.97	$ 0.88	$ 0.79	$ 0.49	$ 3.78	$ 3.14	$ 2.95
Diluted earnings per common share	$ 0.84	$ 1.12	$ 0.97	$ 0.80	$ 0.96	$ 0.87	$ 0.78	$ 0.49	$ 3.73	$ 3.11	$ 2.91
Stock options excluded from computation of EPS									13,500	150,416	64,700

Fair Value Disclosures (Details

Fair Value Disclosures (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, available-for-sale	$ 23,511	$ 24,874
Loans held for sale	1,007,695	968,929
OREO	11,742	18,961	$ 278	$ 568
Municipals
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, available-for-sale		275
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, available-for-sale	12,566	8,947
Fair value measurements, recurring basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	0	0
Derivative assets	0	0
Derivative liabilities	0	0
Non-qualified deferred compensation plan liabilities	5,587	1,811
Fair value measurements, recurring basis | Level 1 | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, available-for-sale	0	0
Fair value measurements, recurring basis | Level 1 | Municipals
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, available-for-sale	0	0
Fair value measurements, recurring basis | Level 1 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, available-for-sale	5,460	1,786
Fair value measurements, recurring basis | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	1,007,695	968,929
Derivative assets	16,719	37,878
Derivative liabilities	17,377	26,240
Non-qualified deferred compensation plan liabilities	0	0
Fair value measurements, recurring basis | Level 2 | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, available-for-sale	10,945	15,652
Fair value measurements, recurring basis | Level 2 | Municipals
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, available-for-sale	0	275
Fair value measurements, recurring basis | Level 2 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, available-for-sale	7,106	7,161
Fair value measurements, recurring basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	0	0
Derivative assets	0	0
Derivative liabilities	0	0
Non-qualified deferred compensation plan liabilities	0	0
Fair value measurements, recurring basis | Level 3 | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, available-for-sale	0	0
Fair value measurements, recurring basis | Level 3 | Municipals
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, available-for-sale	0	0
Fair value measurements, recurring basis | Level 3 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, available-for-sale	0	0
Fair value measurements, nonrecurring basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	0	0
OREO	0	0
Fair value measurements, nonrecurring basis | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	0	0
OREO	0	0
Fair value measurements, nonrecurring basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	21,216	52,323
OREO	$ 11,742	$ 18,961

Fair Value Disclosures (Detai93

Fair Value Disclosures (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Impaired loans
Fair Value Assets Measured On Non Recurring Basis Unobservable Input Reconciliation [Line Items]
Asset measured on nonrecurring basis, carrying value	$ 32,200	$ 74,100
Asset measured on nonrecurring basis, specific valuation allowance	11,000	21,800
Asset measured on nonrecurring basis, reported fair value	21,200	52,300
OREO
Fair Value Assets Measured On Non Recurring Basis Unobservable Input Reconciliation [Line Items]
Asset measured on nonrecurring basis, carrying value	$ 11,742	$ 19,000

Fair Value Disclosures (Detai94

Fair Value Disclosures (Details 2) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities, available-for-sale	$ 23,511	$ 24,874
Loans held for sale	1,007,695	968,929
Subordinated notes	281,406	281,044
Level 1 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities, available-for-sale	2,905,591	2,839,352
Securities, available-for-sale	5,460	1,786
Level 1 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities, available-for-sale	2,905,591	2,839,352
Securities, available-for-sale	5,460	1,786
Level 2 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities, available-for-sale	18,051	23,088
Loans held for sale	1,011,004	968,929
Derivative assets	16,719	37,878
Federal funds purchased	359,338	101,800
Customer repurchase agreements	5,702	7,775
Other borrowings	2,800,000	2,000,000
Subordinated notes	281,406	281,044
Derivative liabilities	17,377	26,240
Level 2 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities, available-for-sale	18,051	23,088
Loans held for sale	1,011,004	968,929
Derivative assets	16,719	37,878
Federal funds purchased	359,338	101,800
Customer repurchase agreements	5,702	7,775
Other borrowings	2,800,000	2,000,000
Subordinated notes	322,415	304,672
Derivative liabilities	17,377	26,240
Level 3 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for investment, net	20,489,757	17,330,223
Deposits	19,123,180	17,016,831
Trust preferred subordinated debentures	113,406	113,406
Level 3 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for investment, net	20,480,802	17,347,199
Deposits	19,124,121	17,017,221
Trust preferred subordinated debentures	$ 113,406	$ 113,406

Commitments and Contingencies95

Commitments and Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Rent expense	$ 15,300	$ 13,900	$ 15,300
Minimum future lease payments under operating leases
2,015	16,446
2,016	16,137
2,017	15,286
2,018	12,805
2,019	12,138
2023 and thereafter	17,299
Total	$ 90,111

Parent Company Only (Details)

Parent Company Only (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jan. 31, 2014	Sep. 21, 2012
Assets
Cash and cash equivalents	$ 2,905,591	$ 2,839,352	$ 1,790,870	$ 1,330,514
Loans held for investment (net of unearned income)	15,366,252	13,001,011
Other assets	516,239	465,933
Total assets	25,075,645	21,697,134
Liabilities and Stockholders’ Equity
Subordinated notes, net	281,406	281,044
Trust preferred subordinated debentures	113,406	113,406			$ 175,000	$ 111,000
Total liabilities	22,872,924	19,687,577
Preferred stock	150,000	150,000
Common stock	496	495
Additional paid-in capital	961,305	955,468
Retained earnings	1,090,500	903,187
Treasury stock	(8)	(8)
Accumulated other comprehensive income	428	415
Total stockholders’ equity	2,202,721	2,009,557	1,623,533	1,484,190
Total liabilities and stockholders’ equity	25,075,645	21,697,134
Texas Capital Bancshares, Inc.
Assets
Cash and cash equivalents	144,635	220,499	$ 53,061	$ 176,324
Loans held for investment (net of unearned income)	7,500	0
Investment in subsidiaries	2,184,601	1,927,392
Other assets	86,300	85,560
Total assets	2,423,036	2,233,451
Liabilities and Stockholders’ Equity
Other liabilities	1,244	1,284
Subordinated notes, net	108,513	108,412
Trust preferred subordinated debentures	113,406	113,406
Total liabilities	223,163	223,102
Preferred stock	150,000	150,000
Common stock	496	495
Additional paid-in capital	971,457	965,620
Retained earnings	1,077,500	893,827
Treasury stock	(8)	(8)
Accumulated other comprehensive income	428	415
Total stockholders’ equity	2,199,873	2,010,349
Total liabilities and stockholders’ equity	$ 2,423,036	$ 2,233,451

Parent Company Only (Details 1)

Parent Company Only (Details 1) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Earnings
Interest on loans									$ 846,292	$ 684,582	$ 594,729
Other non-interest income									10,433	14,178	9,458
Interest expense	$ 38,870	$ 33,282	$ 25,232	$ 20,587	$ 17,448	$ 15,753	$ 15,373	$ 15,020	117,971	63,594	46,428
Salaries and employee benefits									264,231	228,985	192,610
Legal and professional									29,731	23,326	22,150
Other non-interest expense									42,859	37,033	33,398
Income tax expense	50,143	29,850	25,819	22,833	26,149	23,931	21,866	14,132	128,645	86,078	79,641
Net income	44,742	58,684	51,095	42,542	48,386	42,725	38,880	25,128	197,063	155,119	144,854
Preferred stock dividends	2,437	2,438	2,437	2,438	2,437	2,438	2,437	2,438	9,750	9,750	9,750
Net income available to common stockholders	$ 42,305	$ 56,246	$ 48,658	$ 40,104	$ 45,949	$ 40,287	$ 36,443	$ 22,690	187,313	145,369	135,104
Texas Capital Bancshares, Inc.
Statement of Earnings
Interest on loans									3,271	3,250	3,250
Dividend income									10,400	10,400	10,400
Other income									108	90	76
Total income									13,779	13,740	13,726
Other non-interest income									13	152	8
Interest expense									10,908	10,525	9,867
Salaries and employee benefits									489	431	499
Legal and professional									1,700	1,429	1,640
Other non-interest expense									1,761	1,594	1,637
Total expense									14,858	13,979	13,643
Income (loss) before income taxes and equity in undistributed income of subsidiary									(1,066)	(87)	91
Income tax expense									(371)	(33)	33
Income before income taxes									(695)	(54)	58
Equity in undistributed income of subsidiary									194,118	151,445	141,041
Net income									193,423	151,391	141,099
Preferred stock dividends									9,750	9,750	9,750
Net income available to common stockholders									$ 183,673	$ 141,641	$ 131,349

Parent Company Only (Details 2)

Parent Company Only (Details 2) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net income	$ 44,742	$ 58,684	$ 51,095	$ 42,542	$ 48,386	$ 42,725	$ 38,880	$ 25,128	$ 197,063	$ 155,119	$ 144,854
Adjustments to reconcile net income to net cash used in operating activities:
Increase in other assets									(114,551)	(59,787)	(61,002)
Excess tax benefits from stock-based compensation arrangements									0	(2,013)	(1,499)
Increase in other liabilities									10,289	(2,576)	(3,554)
Net cash provided by (used in) operating activities									132,161	(726,293)	68,943
Investing Activities
Net cash used in investing activities									(3,215,745)	(850,210)	(2,460,786)
Financing Activities
Proceeds from sale of common stock									0	236,467	0
Preferred dividends paid									(9,750)	(9,750)	(9,750)
Net other borrowings									800,000	500,000	399,995
Excess tax benefits from stock-based compensation arrangements									0	2,013	1,499
Net cash provided by financing activities									3,149,823	2,624,985	2,852,199
Net increase (decrease) in cash and cash equivalents									66,239	1,048,482	460,356
Cash and cash equivalents at beginning of period				2,839,352				1,790,870	2,839,352	1,790,870	1,330,514
Cash and cash equivalents at end of period	2,905,591				2,839,352				2,905,591	2,839,352	1,790,870
Texas Capital Bancshares, Inc.
Operating activities
Net income									193,423	151,391	141,099
Adjustments to reconcile net income to net cash used in operating activities:
Equity in undistributed income of subsidiary									(194,118)	(151,445)	(141,041)
Amortization									101	101	100
Increase in other assets									(739)	(10)	(2,223)
Excess tax benefits from stock-based compensation arrangements									0	(2,013)	(1,499)
Increase in other liabilities									(40)	165	(209)
Net cash provided by (used in) operating activities									(1,373)	(1,811)	(3,773)
Investing Activities
Net increase in loans held for investment									(7,500)	0	0
Investments in and advances to subsidiaries									(55,000)	(57,000)	(110,000)
Net cash used in investing activities									(62,500)	(57,000)	(110,000)
Financing Activities
Costs from issuance of stock related to stock-based awards and warrants									(2,241)	(2,481)	(1,239)
Proceeds from sale of common stock									0	236,467	0
Preferred dividends paid									(9,750)	(9,750)	(9,750)
Net other borrowings									0	0	0
Excess tax benefits from stock-based compensation arrangements									0	2,013	1,499
Net cash provided by financing activities									(11,991)	226,249	(9,490)
Net increase (decrease) in cash and cash equivalents									(75,864)	167,438	(123,263)
Cash and cash equivalents at beginning of period				$ 220,499				$ 53,061	220,499	53,061	176,324
Cash and cash equivalents at end of period	$ 144,635				$ 220,499				$ 144,635	$ 220,499	$ 53,061

Derivative Financial Instrume99

Derivative Financial Instruments (Details 1) - Non-hedging - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Estimated fair value, asset derivative	$ 21,354	$ 39,632
Estimated fair value, liability derivative	22,012	27,994
Offsetting derivative liabilities	(4,635)	(1,754)
Offsetting derivative assets	(4,635)	(1,754)
Net asset derivatives included in the consolidated balance sheets	16,719	37,878
Net liability derivatives included in the consolidated balance sheets	17,377	26,240
Interest rate contract | Loan purchase commitments
Derivative [Line Items]
Notional amount	253,815	237,805
Estimated fair value, asset derivative	635	1,351
Estimated fair value, liability derivative	190	0
Interest rate contract | Loan purchase commitments
Derivative [Line Items]
Notional amount	1,086,224	1,218,000
Estimated fair value, asset derivative	0	10,287
Estimated fair value, liability derivative	1,103	0
Financial institution counterparties | Commercial loan/lease | Interest rate swap
Derivative [Line Items]
Notional amount	1,393,764	1,144,367
Estimated fair value, asset derivative	4,736	1,754
Estimated fair value, liability derivative	15,482	25,421
Financial institution counterparties | Commercial loan/lease | Interest rate cap
Derivative [Line Items]
Notional amount	242,700	210,996
Estimated fair value, asset derivative	421	819
Estimated fair value, liability derivative	7	0
Financial institution counterparties | Commercial loan/lease | Foreign currency forward contracts
Derivative [Line Items]
Notional amount	2,466	0
Estimated fair value, asset derivative	4	0
Estimated fair value, liability derivative	69	0
Customer counterparties | Commercial loan/lease | Interest rate swap
Derivative [Line Items]
Notional amount	1,393,764	1,144,367
Estimated fair value, asset derivative	15,482	25,421
Estimated fair value, liability derivative	4,736	1,754
Customer counterparties | Commercial loan/lease | Interest rate cap
Derivative [Line Items]
Notional amount	242,700	210,996
Estimated fair value, asset derivative	7	0
Estimated fair value, liability derivative	421	819
Customer counterparties | Commercial loan/lease | Foreign currency forward contracts
Derivative [Line Items]
Notional amount	2,466	0
Estimated fair value, asset derivative	69	0
Estimated fair value, liability derivative	$ 4	$ 0

Derivative Financial Instrum100

Derivative Financial Instruments Derivative Financial Instruments (Details 2) - Non-hedging - Commercial loan/lease - Interest rate swap	Dec. 31, 2017	Dec. 31, 2016
Interest rate received
Derivative [Line Items]
Weighted average fixed interest rate	3.59%	3.17%
Interest rate paid
Derivative [Line Items]
Weighted average fixed interest rate	4.34%	4.58%

Derivative Financial Instrum101

Derivative Financial Instruments Derivative Financial Instruments (Details 3)	Dec. 31, 2017USD ($)instrument	Dec. 31, 2016USD ($)
Derivative [Line Items]
Cash collateral pledged for derivatives	$ 15,200,000	$ 24,800,000
Risk participation agreement - participant bank
Derivative [Line Items]
Instruments held | instrument	15
Maximum exposure	$ 221,000
Notional amount	$ 157,000,000
Risk participation agreement - lead bank
Derivative [Line Items]
Instruments held | instrument	10
Notional amount	$ 86,300,000
Non-hedging | Commercial loan/lease
Derivative [Line Items]
Credit risk exposure, net of collateral pledged, relating to derivatives	$ 16,700,000	$ 37,900,000
Non-hedging | Interest rate cap | Commercial loan/lease
Derivative [Line Items]
Weighted average fixed interest rate	2.40%	2.45%
Interest-bearing deposits
Derivative [Line Items]
Cash collateral pledged for derivatives	$ 14,000,000
Other assets
Derivative [Line Items]
Cash collateral pledged for derivatives	$ 1,200,000

Stockholder's Equity (Details)

Stockholder's Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 02, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity Distribution Agreement [Line Items]
Net proceeds from issuance of stock		$ 0	$ 236,467
Par value of preferred stock		$ 0.01	$ 0.01
Payments of dividends on preferred stock		$ 9,750	$ 9,750	$ 9,750
Common Stock
Equity Distribution Agreement [Line Items]
Net proceeds from issuance of stock	$ 236,400	$ 0	$ 35
Issuance of stock - shares	3,450,000	0	3,450,000
Repayments of short-term debt	$ 0

Quarterly Financial Data (Detai

Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Selected Quarterly Financial Information [Abstract]
Interest income	$ 249,519	$ 237,643	$ 208,191	$ 183,946	$ 188,671	$ 182,492	$ 172,442	$ 159,803	$ 879,299	$ 703,408	$ 602,958
Interest expense	38,870	33,282	25,232	20,587	17,448	15,753	15,373	15,020	117,971	63,594	46,428
Net interest income	210,649	204,361	182,959	163,359	171,223	166,739	157,069	144,783	761,328	639,814	556,530
Provision for credit losses	2,000	20,000	13,000	9,000	9,000	22,000	16,000	30,000	44,000	77,000	53,250
Net interest income after provision for credit losses	208,649	184,361	169,959	154,359	162,223	144,739	141,069	114,783	717,328	562,814	503,280
Non-interest income	19,374	19,003	18,769	17,110	18,835	16,716	13,932	11,297	74,256	60,780	47,738
Non-interest expense	133,138	114,830	111,814	106,094	106,523	94,799	94,255	86,820	465,876	382,397	326,523
Income before income taxes	94,885	88,534	76,914	65,375	74,535	66,656	60,746	39,260	325,708	241,197	224,495
Income tax expense	50,143	29,850	25,819	22,833	26,149	23,931	21,866	14,132	128,645	86,078	79,641
Net income	44,742	58,684	51,095	42,542	48,386	42,725	38,880	25,128	197,063	155,119	144,854
Preferred stock dividends	2,437	2,438	2,437	2,438	2,437	2,438	2,437	2,438	9,750	9,750	9,750
Net income available to common stockholders	$ 42,305	$ 56,246	$ 48,658	$ 40,104	$ 45,949	$ 40,287	$ 36,443	$ 22,690	$ 187,313	$ 145,369	$ 135,104
Basic earnings per share:
Basic earnings per common share	$ 0.85	$ 1.13	$ 0.98	$ 0.81	$ 0.97	$ 0.88	$ 0.79	$ 0.49	$ 3.78	$ 3.14	$ 2.95
Diluted earnings per share:
Diluted earnings per common share	$ 0.84	$ 1.12	$ 0.97	$ 0.80	$ 0.96	$ 0.87	$ 0.78	$ 0.49	$ 3.73	$ 3.11	$ 2.91
Average shares
Basic	49,630,000	49,607,000	49,577,000	49,536,000	47,156,000	45,981,000	45,924,000	45,889,000	49,587,169	46,239,210	45,808,440
Diluted	50,312,000	50,251,000	50,230,000	50,234,000	47,760,000	46,510,000	46,438,000	46,354,000	50,259,834	46,765,902	46,437,872