Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Gain (Loss) on Sale of Insurance Block	$ 0	$ (1,514)
Repayments of junior subordinated debt	8,248	0
Cash Flows From Operating Activities
Net income	39,970	29,199
Adjustments to reconcile net income to net cash provided by operating activities
Provision for loan and lease losses	5,852	2,775
Stock-based compensation expense	2,064	2,358
Depreciation, amortization and accretion	7,618	6,074
Investment securities gains, net	22	0
Net realized (gain) loss on sale of premises and equipment, loans held for investment and other assets	(630)	55
Net realized loss on sale and valuation adjustments of other real estate owned	135	204
Originations of loans held for sale	27,553	31,295
Proceeds from sales of loans held for sale	29,007	33,896
Net change in:
Interest receivable	(914)	(1,271)
Interest payable	452	(9)
Other assets	2,530	(650)
Other liabilities	(15,014)	(3,841)
Net cash provided by operating activities	43,495	35,981
Cash Flows From Investing Activities
Loans originated and acquired, net of principal collected	17,688	(21,936)
Purchases of securities available for sale	(27,497)	(108,958)
Purchases of premises and equipment	(2,099)	(336)
Payments to Acquire Federal Home Loan Bank Stock	(45,080)	(31,400)
Proceeds from FDIC for reimbursement on loss-sharing asset	0	26
Proceeds from sales of securities available for sale	19,761	0
Proceeds from principal repayments and maturities of securities available for sale	82,643	55,369
Proceeds from Sales of Assets, Investing Activities	3,721	6,893
Proceeds from Sale of Federal Home Loan Bank Stock	43,880	31,040
Proceeds from sales of other real estate and other personal property owned	2,062	1,275
Payments to FDIC related to loss-sharing asset	0	(210)
Net cash provided by (used in) investing activities	95,079	(68,237)
Cash Flows From Financing Activities
Net (decrease) increase in deposits	(136,466)	29,433
Net decrease in sweep repurchase agreements	(54,812)	(33,908)
Proceeds from Federal Home Loan Bank advances	1,127,000	785,000
Proceeds from exercise of stock options	719	1,145
Repayment of Federal Home Loan Bank advances	(1,097,000)	(776,000)
Payment of common stock dividends	(16,069)	(12,792)
Purchase and retirement of common stock	2,575	2,039
Net cash used in financing activities	(187,451)	(9,161)
Decrease in cash and cash equivalents	(48,877)	(41,417)
Cash and cash equivalents at beginning of period	342,533	224,238
Cash and cash equivalents at end of period	293,656	182,821
Supplemental Information:
Cash paid for interest	3,211	1,150
Cash paid for income tax	24	0
Non-cash investing and financing activities
Loans transferred to other real estate owned	$ 406	$ 0