Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities:
Net income	$ 206,875	$ 156,749	$ 151,398
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	34,084	32,942	20,537
Depreciation, amortization and accretion, net	53,148	41,010	37,792
Deferred income tax expense	6,676	23,054	4,125
Stock-based compensation expense	9,303	9,656	7,754
Excess tax benefits from stock-based compensation arrangements	(951)	(744)	(444)
Net amortization of premium on securities	5,646	3,398	1,498
Accretion of discounts on loans	(35,571)	(34,378)	(42,539)
Mortgage servicing rights fair value change, net	3,405	(213)	1,428
Originations and purchases of mortgage loans held-for-sale	(4,386,339)	(3,903,777)	(3,182,684)
Proceeds from sales of mortgage loans held-for-sale	4,468,984	3,971,724	3,241,489
BOLI income	(3,594)	(3,146)	(2,701)
(Increase) decrease in trading securities, net	(1,541)	758	(709)
Net decrease (increase) in brokerage customer receivables	2,450	(3,410)	6,732
Gains on mortgage loans sold	(112,981)	(104,695)	(75,768)
(Gains) losses on investment securities, net	(7,645)	(323)	504
Gains on early extinguishment of debt, net	(3,588)	0	0
(Gains) losses on sales of premises and equipment, net	(305)	807	644
Net losses (gains) on sales and fair value adjustments of other real estate owned	1,381	(350)	3,735
(Increase) decrease in accrued interest receivable and other assets, net	(43,614)	(151,132)	72,479
Increase (decrease) in accrued interest payable and other liabilities, net	113,258	292	(38,902)
Net Cash Provided by Operating Activities	309,081	38,222	206,368
Investing Activities:
Proceeds from maturities of available-for-sale securities	1,234,162	506,798	431,347
Proceeds from maturities of held-to-maturity securities	710	55	0
Proceeds from sales and calls of available-for-sale securities	2,208,010	1,515,559	852,330
Proceeds from calls of held-to-maturity securities	734,326	770	0
Purchases of available-for-sale securities	(3,398,640)	(2,092,652)	(1,597,587)
Purchases of held-to-maturity securities	(486,696)	(22,892)	0
Purchase of Federal Home Loan Bank and Federal Reserve Bank stock, net	(31,913)	(9,999)	(12,321)
Net cash (paid) received in business combinations	(613,619)	(15,428)	228,946
Proceeds from sales of other real estate owned	38,367	50,405	92,620
Proceeds received from the FDIC related to reimbursements on covered assets	1,207	1,859	19,999
Net (increase) decrease in interest-bearing deposits with banks	(366,591)	531,396	(502,863)
Net increase in loans	(1,779,905)	(2,066,666)	(1,311,927)
Redemption of BOLI	1,840	2,701	0
Purchases of premises and equipment, net	(33,923)	(43,459)	(38,136)
Net Cash Used for Investing Activities	(2,492,665)	(1,641,553)	(1,837,592)
Financing Activities:
Increase in deposit accounts	2,769,022	1,381,425	1,217,396
(Decrease) increase in subordinated notes and other borrowings, net	(3,405)	44,415	(59,384)
(Decrease) increase in Federal Home Loan Bank advances, net	(707,594)	115,186	315,550
Proceeds from the issuance of common stock, net	152,911	0	0
Proceeds from the issuance of preferred stock, net	0	120,842	0
Proceeds from the issuance of subordinated notes, net	0	0	139,090
Redemption of junior subordinated debentures, net	(10,695)	0	0
Excess tax benefits from stock-based compensation arrangements	951	744	444
Issuance of common shares resulting from exercise of stock options, employee stock purchase plan and conversion of common stock warrants	15,828	16,119	10,453
Common stock repurchases	(616)	(424)	(549)
Dividends paid	(38,568)	(29,888)	(24,933)
Net Cash Provided by Financing Activities	2,177,834	1,648,419	1,598,067
Net (Decrease) Increase in Cash and Cash Equivalents	(5,750)	45,088	(33,157)
Cash and Cash Equivalents at Beginning of Period	275,795	230,707	263,864
Cash and Cash Equivalents at End of Period	270,045	275,795	230,707
Cash paid during the year for:
Interest	91,390	77,737	73,334
Income taxes, net	94,888	94,723	72,575
Acquisitions:
Fair value of assets acquired, including cash and cash equivalents	882,865	1,187,115	475,398
Value ascribed to goodwill and other intangible assets	27,083	79,879	37,526
Fair value of liabilities assumed	259,631	1,033,219	405,801
Non-cash activities
Transfer of available-for-sale securities to held-to-maturity securities	0	862,712	0
Transfer to other real estate owned from loans	13,352	28,565	52,102
Common stock issued for acquisitions	$ 0	$ 38,723	$ 0