Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities:
Net income	$ 355,697	$ 343,166	$ 257,682
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	53,864	34,832	29,768
Depreciation, amortization and accretion, net	88,362	67,665	63,107
Deferred income tax expense	44,557	55,224	63,243
Stock-based compensation expense	11,304	13,496	12,858
Net amortization of premium on securities	6,605	7,411	6,098
Accretion of discounts on loans	(26,624)	(20,318)	(22,784)
Mortgage servicing rights fair value change, net	35,536	5,370	1,857
Originations and purchases of mortgage loans held-for-sale	(4,497,921)	(3,955,438)	(3,692,085)
Proceeds from sales of mortgage loans held-for-sale	4,484,838	4,076,887	3,869,137
BOLI income	(4,846)	(5,448)	(3,524)
Decrease (increase) in trading securities, net	624	(697)	994
Net (increase) decrease in brokerage customer receivables	(3,964)	13,822	(1,250)
Gains on mortgage loans sold	(135,607)	(104,998)	(88,699)
(Gains) losses on investment securities, net, and dividend reinvestment on equity securities	(3,525)	2,000	(45)
Losses (gains) on sales of premises and equipment, net	92	64	(192)
Net losses on sales and fair value adjustments of other real estate owned	1,921	4,664	639
Gain on termination of loss share agreements with the FDIC	0	0	(385)
Increase in accrued interest receivable and other assets, net	(133,022)	(133,519)	(126,583)
(Decrease) increase in accrued interest payable and other liabilities, net	(11,898)	(27,001)	31,790
Net Cash Provided by Operating Activities	265,993	377,182	401,626
Investing Activities:
Proceeds from maturities and calls of available-for-sale securities	718,345	352,683	276,097
Proceeds from maturities and calls of held-to-maturity securities	422,959	11,129	108,943
Proceeds from sales of available-for-sale securities	972,253	214,196	344,674
Proceeds from sales of equity securities with readily determinable fair value	19,200	1,895	0
Proceeds from sales and capital distributions of equity securities without readily determinable fair value	1,764	1,324	0
Purchases of available-for-sale securities	(2,226,834)	(1,095,375)	(774,041)
Purchases of held-to-maturity securities	(493,389)	(253,129)	(301,909)
Purchases of equity securities with readily determinable fair value	(32,729)	0	0
Purchases of equity securities without readily determinable fair value	(4,394)	(4,592)	0
(Purchase) redemption of Federal Home Loan Bank and Federal Reserve Bank stock, net	(9,385)	(1,365)	43,505
Distributions from investments in partnerships, net	1,955	3,409	512
Net cash paid in business combinations	(108,365)	(53,871)	(284)
Proceeds from sales of other real estate owned	14,516	19,375	18,742
Proceeds paid to the FDIC related to reimbursements on covered assets	0	0	(15,411)
Net increase in interest-bearing deposits with banks	(983,513)	(15,988)	(81,621)
Net increase in loans	(2,229,637)	(1,883,354)	(1,863,245)
Redemption of BOLI	326	8,438	0
Purchases of premises and equipment, net	(82,021)	(68,273)	(59,194)
Net Cash Used for Investing Activities	(4,018,949)	(2,763,498)	(2,303,232)
Financing Activities:
Increase in deposit accounts	3,142,499	2,547,399	1,524,848
Increase (decrease) in other borrowings, net	15,480	137,257	(4,888)
Increase (decrease) in Federal Home Loan Bank advances, net	248,442	(147,999)	403,000
Cash payments to settle contingent consideration liabilities recognized in business combinations	(66)	0	(1,097)
Proceeds from the issuance of subordinated notes, net	296,617	0	0
Issuance of common shares resulting from exercise of stock options, employee stock purchase plan and conversion of common stock warrants	10,667	15,903	28,229
Common stock repurchases for tax withholdings related to stock-based compensation	(1,297)	(648)	(397)
Dividends paid	(65,110)	(50,987)	(40,543)
Net Cash Provided by Financing Activities	3,647,232	2,500,925	1,909,152
Net (Decrease) Increase in Cash and Cash Equivalents	(105,724)	114,609	7,546
Cash and Cash Equivalents at Beginning of Period	392,200	277,591	270,045
Cash and Cash Equivalents at End of Period	286,476	392,200	277,591
Cash paid during the year for:
Interest	327,329	197,911	112,783
Income taxes, net	60,845	69,118	76,812
Business combinations and asset acquisitions:
Fair value of assets acquired, including cash and cash equivalents	1,093,254	485,368	1,022
Value ascribed to goodwill and other intangible assets	80,581	109,548	999
Fair value of liabilities assumed	896,686	423,234	738
Non-cash activities
Transfer to other real estate owned from loans	5,722	7,936	15,013
Common stock issued for acquisitions	$ 71,756	$ 0	$ 0