Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows From Operating Activities
Net income	$ 112,828	$ 104,866	$ 98,827
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses	8,631	10,778	8,591
Stock-based compensation expense	7,745	5,009	4,090
Depreciation, amortization and accretion	31,101	34,542	30,312
Investment securities loss (gain), net	11	(1,181)	(1,581)
Net realized loss (gain) on sale of premises and equipment, loans held for investment and other assets	(139)	157	573
Net gain on sale and valuation adjustments of OREO	(495)	(629)	2,152
Gain on sale of merchant card services portfolio	(14,000)	0	0
Gain (Loss) on Sale of Insurance Block	(4,193)	0	0
FDIC loss-sharing agreement early termination, pretax charge	2,409	0	0
Originations of loans held for sale	(133,460)	(110,467)	(75,689)
Proceeds from Sale of Loans Held-for-sale	133,540	109,130	72,296
Deferred income tax expense (benefit)	22,431	1,846	6,367
Net change in:
Interest receivable	(2,980)	(2,197)	(75)
Interest payable	131	(93)	(142)
Other assets	(25,471)	(15,917)	(5,419)
Other liabilities	(10,554)	8,745	(1,242)
Net cash provided by operating activities	128,525	145,847	134,756
Cash Flows From Investing Activities
Payments for (Proceeds from) Loans and Leases	(273,927)	(402,146)	(384,321)
Purchases of securities available for sale	(355,607)	(569,825)	(467,631)
Purchases of premises and equipment	(6,495)	(4,520)	(7,581)
Payments to Acquire Federal Home Loan Bank Stock	(92,040)	(59,599)	(16,760)
Proceeds from FDIC for reimbursement on loss-sharing asset	26	927	4,659
Proceeds from sales of securities available for sale	30,403	124,142	95,375
Proceeds from principal repayments and maturities of securities available for sale	283,874	284,218	283,206
Proceeds from sales of loans held for investment and other assets	12,422	9,643	15,074
Proceeds from sale of merchant card services portfolio	14,000	0	0
Proceeds from Sale of Federal Home Loan Bank Stock	98,924	62,081	37,403
Proceeds from sales of other real estate and other personal property owned	2,590	8,158	19,387
Proceeds from Life Insurance Policy	10,745	0	0
Payment from (to) FDIC to terminate loss-sharing agreements	(4,666)	0	0
Payment to FDIC Related to Loss-Sharing Asset	(210)	(1,632)	(1,865)
Net cash received in business combinations	80,472	0	0
Net cash used in investing activities	(199,489)	(548,553)	(423,054)
Cash Flows From Financing Activities
Net increase (decrease) in deposits	353,797	620,785	514,107
Net decrease in repurchase agreements	(3,380)	(18,877)	(5,381)
Proceeds from exercise of stock options	1,980	1,349	1,258
Proceeds from Federal Home Loan Bank advances	2,301,000	1,392,000	1,702,000
Proceeds from Federal Reserve Bank borrowings	10	10	1,010
Repayment of Federal Home Loan Bank advances	(2,397,000)	(1,454,000)	(1,850,000)
Repayment of Federal Reserve Bank borrowings	(10)	(10)	(1,010)
Payment of preferred stock dividends	0	(157)	(137)
Payment of common stock dividends	(51,308)	(88,677)	(77,263)
Repayments of Subordinated Debt	6,186	0	8,248
Payments for Repurchase of Equity	(7,345)	0	0
Purchase and retirement of common stock	(2,299)	(1,125)	(906)
Proceeds from excess tax benefit from stock-based compensation	0	(344)	0
Net cash provided by financing activities	189,259	451,642	275,430
Increase (decrease) in cash and cash equivalents	118,295	48,936	(12,868)
Cash and cash equivalents at beginning of period	224,238	175,302	188,170
Supplemental Information:
Cash paid for interest	6,626	4,444	4,146
Cash paid for income tax	59,071	32,723	30,522
Non-cash investing and financing activities
Loans transferred to other real estate owned	106	1,047	8,688
Share-based consideration issued in business combinations	$ 636,385	$ 0	$ 0