Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net income	$ 70,170	$ 47,604
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	6,256	4,050
Gains on sales of loans	(1,508)	(6,120)
Proceeds from sales of loans	190,435	191,531
Loans originated for sale	(165,823)	(142,704)
Net gains on sale of investment securities	0	(90)
Net gains from sales/writedowns of other real estate and repossessed assets	(71)	(700)
Depreciation of premises and equipment	4,129	4,521
Amortization of intangible assets	1,438	1,513
Additions to loan servicing rights	(1,967)	(1,753)
Valuation change in loan servicing rights	(3,029)	1,125
Net amortization of premiums and discounts on investment securities	4,298	4,129
Share-based compensation expense	1,652	3,734
Deferred income tax (benefit) expense	(1,638)	17,948
Change in deferred tax valuation allowance	(49)	0
Net decrease (increase) in interest receivable and other assets	12,856	(29,773)
Net decrease in interest payable and other liabilities	(9,060)	(19,282)
Net cash provided by operating activities	108,089	75,733
Debt securities – available-for-sale:
Proceeds from maturities, calls and principal reductions	66,526	60,885
Purchases	(431,670)	(102,702)
Investment securities – held-to-maturity:
Proceeds from maturities, calls and principal reductions	8,744	9,408
Purchases	(8,835)	(33,628)
Net increase in loans	(71,952)	(290,438)
Proceeds from sales of other real estate and repossessed assets	3,351	5,734
Purchases of premises and equipment, net of disposals	(3,484)	(2,272)
Proceeds from returns of investment in equity method investments	266	113
Net cash used in investing activities	(437,054)	(352,900)
Cash flows from financing activities
Net increase in interest- and noninterest-bearing demand deposits and savings accounts	182,108	350,763
Net increase (decrease) in time deposits	142,906	(91,538)
Net increase in collateralized customer deposits and other short-term borrowings	124,871	130,863
Repayment of long-term borrowings	0	(107,000)
Cash dividends paid	(20,075)	(19,271)
Proceeds from directors’ stock plans and exercise of stock options, net of shares withheld	952	1,578
Cash paid for payroll taxes upon conversion of share-based awards	(4,295)	(20,850)
Net cash provided by financing activities	426,467	244,545
Net increase (decrease) in cash and cash equivalents	97,502	(32,622)
Cash and cash equivalents at beginning of period	455,991	474,402
Cash and cash equivalents at end of period	553,493	441,780
Supplemental disclosures of cash flow information:
Interest paid	25,038	12,989
Income tax refunds, net of income taxes paid	(441)	(24,397)
Non-cash activities:
Loans transferred to other real estate and repossessed assets	2,484	4,281
Net transfer of loans held-for-sale to loans held- for-investment	$ (2,607)	$ 0