Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows From Operating Activities
Net income	$ 172,882	$ 112,828	$ 104,866
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses	14,769	8,631	10,778
Stock-based compensation expense	8,354	7,745	5,009
Depreciation, amortization and accretion	32,971	31,101	34,542
Investment securities loss (gain), net	89	11	(1,181)
Net realized loss (gain) on sale of premises and equipment and loans held for investment	316	(139)	157
Net gain on sale and valuation adjustments of OREO	(1,218)	(495)	(629)
Gain on sale of merchant card services portfolio	0	(14,000)	0
Gain (Loss) on Sale of Insurance Block	0	(4,193)	0
FDIC loss-sharing agreement early termination, pretax charge	0	2,409	0
Originations of loans held for sale	(133,945)	(133,460)	(110,467)
Proceeds from Sale of Loans Held-for-sale	135,862	133,540	109,130
Deferred income tax expense (benefit)	108	22,431	1,846
Net change in:
Interest receivable	(4,442)	(2,980)	(2,197)
Interest payable	164	131	(93)
Other assets	2,176	(25,471)	(15,917)
Other liabilities	6,679	(10,554)	8,745
Net cash provided by operating activities	237,201	128,525	145,847
Cash Flows From Investing Activities
Payments for (Proceeds from) Loans and Leases	2,069	(273,927)	(402,146)
Purchases of securities available for sale	(965,585)	(355,607)	(569,825)
Payments to Acquire Loans Held-for-investment	(46,969)	0	0
Purchases of premises and equipment	(11,328)	(6,495)	(4,520)
Payments to Acquire Federal Home Loan Bank Stock	(197,440)	(92,040)	(59,599)
Proceeds from FDIC for reimbursement on loss-sharing asset	0	26	927
Proceeds from sales of securities available for sale	32,330	30,403	124,142
Proceeds from Sale of Available-for-sale Securities, Equity	4,808	0	0
Proceeds from principal repayments and maturities of securities available for sale	465,747	283,874	284,218
Proceeds from sales of loans held for investment and other assets	16,030	12,422	9,643
Proceeds from sale of merchant card services portfolio	0	14,000	0
Proceeds from Sale of Federal Home Loan Bank Stock	181,920	98,924	62,081
Proceeds from sales of other real estate and other personal property owned	7,261	2,590	8,158
Proceeds from Life Insurance Policy	5,074	10,745	0
Payment from (to) FDIC to terminate loss-sharing agreements	0	(4,666)	0
Payment to FDIC Related to Loss-Sharing Asset	0	(210)	(1,632)
Net cash received in business combinations	0	80,472	0
Net cash used in investing activities	(506,083)	(199,489)	(548,553)
Cash Flows From Financing Activities
Net increase (decrease) in deposits	(73,591)	353,797	620,785
Net increase (decrease) in sweep repurchase agreements	7,035	(3,380)	(18,877)
Proceeds from exercise of stock options	1,857	1,980	1,349
Proceeds from Federal Home Loan Bank advances	4,936,000	2,301,000	1,392,000
Proceeds from Federal Reserve Bank borrowings	5,010	10	10
Repayment of Federal Home Loan Bank advances	(4,548,000)	(2,397,000)	(1,454,000)
Repayment of Federal Reserve Bank borrowings	(5,010)	(10)	(10)
Payment of preferred stock dividends	0	0	(157)
Payment of common stock dividends	(83,440)	(51,308)	(88,677)
Repayments of Subordinated Debt	8,248	6,186	0
Repayment of term repurchase agreement	(25,000)	0	0
Payments for Repurchase of Equity	0	(7,345)	0
Purchase and retirement of common stock	(2,677)	(2,299)	(1,125)
Proceeds from excess tax benefit from stock-based compensation	0	0	(344)
Net cash provided by financing activities	203,936	189,259	451,642
Increase (decrease) in cash and cash equivalents	(64,946)	118,295	48,936
Cash and cash equivalents at beginning of period	342,533	224,238	175,302
Supplemental Information:
Cash paid for interest	18,066	6,626	4,444
Cash paid for income tax	24,067	59,071	32,723
Non-cash investing and financing activities
Loans transferred to other real estate owned	1,200	106	1,047
Share-based consideration issued in business combinations	0	636,385	0
Capital Expenditures Incurred but Not yet Paid	195	0	0
Change in dividends payable on unvested shares	$ 19	$ 0	$ 0