Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities
Net income	$ 62,942	$ 71,596
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	2,059	6,256
Gains on sales of loans	(6,150)	(1,508)
Proceeds from sales of loans	195,833	190,435
Valuation change in loans held-for-sale	2,074	700
Loans originated for sale, net of repayments	(130,320)	(165,823)
Net gains on sale of investment securities	(87)	0
Net gains from sales/writedowns of other real estate and repossessed assets	(432)	(71)
Depreciation of premises and equipment	4,234	4,129
Amortization of intangible assets	1,361	1,438
Additions to loan servicing rights	(2,133)	(1,967)
Valuation change in loan servicing rights	8,445	(3,029)
Net amortization of premiums and discounts on investment securities	5,892	4,298
Share-based compensation expense	2,373	1,652
Deferred income tax expense	3,735	5,356
Change in deferred tax valuation allowance	0	(49)
Cash paid for amounts related to operating leases	(1,937)	0
Net (increase) decrease in interest receivable and other assets	(34,462)	4,436
Net increase (decrease) in interest payable and other liabilities	38,526	(9,060)
Net cash provided by operating activities	151,953	108,789
Investment securities - carried at fair value
Proceeds from maturities, calls and principal reductions	95,148	66,526
Proceeds from sales and redemptions	71,502	0
Purchases	(414,624)	(431,670)
Investment securities – held-to-maturity:
Proceeds from maturities, calls and principal reductions	2,859	8,744
Purchases	(975)	(8,835)
Net increase in loans	(60,847)	(71,952)
Proceeds from sales of other real estate and repossessed assets	2,295	3,351
Purchases of premises and equipment, net of disposals	(3,244)	(3,484)
Proceeds from returns of investment in equity method investments	110	266
Net cash used in investing activities	(307,776)	(437,054)
Cash flows from financing activities
Net increase in interest- and noninterest-bearing demand deposits and savings accounts	208,296	182,108
Net increase in time deposits	260,421	142,906
Net (decrease) increase in collateralized customer deposits and other short-term borrowings	(264,488)	124,871
Cash dividends paid	(24,486)	(20,075)
Proceeds from directors’ stock plans and exercise of stock options, net of shares withheld	388	952
Cash paid for payroll taxes upon conversion of share-based awards	(2,571)	(4,295)
Net cash provided by financing activities	177,560	426,467
Net increase in cash and cash equivalents	21,737	98,202
Cash and cash equivalents at beginning of period	495,839	455,991
Cash and cash equivalents at end of period	517,576	554,193
Supplemental disclosures of cash flow information:
Interest paid	49,753	25,038
Net income tax refunds	(24,749)	(441)
Non-cash activities:
Loans transferred to other real estate and repossessed assets	4,877	2,484
Net transfer of loans held-for-sale to (from) loans held-for-investment	$ 58
Net transfer of loans held-for-sale to (from) loans held-for-investment		$ (3,307)