Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating Activities:
Net income	$ 171,561	$ 123,275
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	13,389	14,100
Depreciation, amortization and accretion, net	31,986	29,958
Stock-based compensation expense	7,098	5,746
Net amortization of premium on securities	4,069	3,198
Accretion of discount on loans	(9,860)	(11,979)
Mortgage servicing rights fair value change, net	(3,664)	(1,265)
Originations and purchases of mortgage loans held-for-sale	(1,875,225)	(1,856,725)
Proceeds from sales of mortgage loans held-for-sale	1,770,257	1,928,870
Bank owned life insurance (BOLI) income	(2,258)	(1,873)
Decrease in trading securities, net	133	2
Net decrease in brokerage customer receivables	9,782	1,900
Gains on mortgage loans sold	(49,200)	(43,547)
Losses on investment securities, net	339	8
Losses (gains) on sales of premises and equipment, net	18	(140)
Net losses on sales and fair value adjustments of other real estate owned	3,008	896
Increase in accrued interest receivable and other assets, net	(61,083)	(45,232)
Increase (decrease) in accrued interest payable and other liabilities, net	92,374	(21,393)
Net Cash Provided by Operating Activities	102,724	125,799
Investing Activities:
Proceeds from maturities and calls of available-for-sale securities	133,209	143,983
Proceeds from maturities and calls of held-to-maturity securities	6,014	101,547
Proceeds from sales of available-for-sale securities	208,991	3,676
Proceeds from sales and capital distributions of equity securities without readily determinable fair value	616	0
Purchases of available-for-sale securities	(475,998)	(184,659)
Purchases of held-to-maturity securities	(70,993)	(256,094)
Purchases of equity securities without readily determinable fair value	(2,741)	0
(Purchase) redemption of Federal Home Loan Bank and Federal Reserve Bank stock, net	(6,710)	52,682
Net cash paid in business combinations	(18,708)	(284)
Proceeds from sales of other real estate owned	8,236	8,601
Proceeds received from the FDIC related to reimbursements on covered assets	0	791
Net increase in interest bearing deposits with banks	(160,456)	(31,178)
Net increase in loans	(937,503)	(1,032,772)
Redemption of BOLI	2,121	0
Purchases of premises and equipment, net	(32,318)	(26,260)
Net Cash Used for Investing Activities	(1,346,240)	(1,219,967)
Financing Activities:
Increase in deposit accounts	1,182,140	947,150
(Decrease) increase in subordinated notes and other borrowings, net	(4,489)	15,163
Increase in Federal Home Loan Bank advances, net	107,000	163,000
Cash payments to settle contingent consideration liabilities recognized in business combinations	0	(1,058)
Issuance of common shares resulting from the exercise of stock options, employee stock purchase plan and conversion of common stock warrants	11,747	17,120
Common stock repurchases for tax withholdings related to stock-based compensation	(369)	(295)
Dividends paid	(25,462)	(20,796)
Net Cash Provided by Financing Activities	1,270,567	1,120,284
Net Decrease in Cash and Cash Equivalents	27,051	26,116
Cash and Cash Equivalents at Beginning of Period	277,591	270,045
Cash and Cash Equivalents at End of Period	$ 304,642	$ 296,161