Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash Flows From Operating Activities
Net income	$ 81,719	$ 56,331
Adjustments to reconcile net income to net cash provided by operating activities
Provision for loan and lease losses	9,827	5,952
Stock-based compensation expense	4,083	4,114
Depreciation, amortization and accretion	16,788	13,968
Investment securities losses, net	(11)	0
Net realized (gain) loss on sale of premises and equipment, loans held for investment and other assets	141	(176)
Net realized loss on sale and valuation adjustments of other real estate owned	803	221
Gain on bank owned life insurance death benefit	0	1,945
FDIC loss-sharing agreement early termination, pretax charge	0	2,409
Originations of loans held for sale	67,311	65,902
Proceeds from sales of loans held for sale	66,304	64,830
Net change in:
Interest receivable	(2,224)	(782)
Interest payable	(36)	35
Other assets	6,367	(12,580)
Other liabilities	(2,017)	(9,230)
Net cash provided by operating activities	114,455	57,245
Cash Flows From Investing Activities
Loans originated, net of principal collected	(100,485)	(216,541)
Purchases of securities available for sale	(215,612)	(114,309)
Purchases of premises and equipment	(5,011)	(1,947)
Payments to Acquire Federal Home Loan Bank Stock	(89,720)	(86,840)
Proceeds from FDIC for reimbursement on loss-sharing asset	0	26
Proceeds from sales of securities available for sale	32,330	0
Proceeds from principal repayments and maturities of securities available for sale	219,683	131,472
Proceeds from Sales of Assets, Investing Activities	6,236	8,133
Proceeds from Sale of Federal Home Loan Bank Stock	86,200	80,720
Proceeds from sales of other real estate and other personal property owned	5,821	1,719
Proceeds from Life Insurance Policy	5,074	8,538
Payment from (to) FDIC to terminate loss-sharing agreements	0	(4,666)
Payments to FDIC related to loss-sharing asset	0	(210)
Net cash used in investing activities	(55,484)	(193,905)
Cash Flows From Financing Activities
Net (decrease) increase in deposits	(147,891)	13,078
Net decrease in sweep repurchase agreements	(32,830)	(14,927)
Proceeds from Federal Home Loan Bank advances	2,243,000	2,171,000
Federal Reserve Bank borrowings	10	10
Proceeds from exercise of stock options	736	1,155
Repayment of Federal Home Loan Bank advances	(2,155,000)	(2,018,000)
Repayment of Federal Reserve Bank borrowings	10	10
Payment of common stock dividends	(35,105)	(25,621)
Repayments of junior subordinated debt	8,248	0
Purchase and retirement of common stock	2,627	2,215
Net cash provided by (used in) financing activities	(137,965)	124,470
Decrease in cash and cash equivalents	(78,994)	(12,190)
Cash and cash equivalents at beginning of period	342,533	224,238
Cash and cash equivalents at end of period	263,539	212,048
Supplemental Information:
Cash paid for interest	7,573	2,731
Cash paid for income tax	3,621	22,881
Non-cash investing and financing activities
Loans transferred to other real estate owned	406	0
Premises and equipment expenditures incurred but not yet paid	$ 40	$ 0