Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Activities
Net income	$ 284,757	$ 266,400	$ 210,544
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	23,076	39,765	57
Net amortization of debt securities	47,299	16,893	12,985
Net amortization of purchase accounting adjustments and deferred loan fees and costs	(17,881)	(57,627)	(3,712)
Amortization of debt modification costs	0	0	4,630
Origination of loans held for sale	(1,550,787)	(2,070,843)	(983,988)
Proceeds from loans held for sale	1,797,566	2,093,549	985,345
Gain on sale of loans	(63,063)	(99,450)	(34,064)
Loss (gain) on sale of debt securities	638	(1,139)	(14,415)
Bank-owned life insurance income, net	(2,873)	(2,724)	(2,245)
Stock-based compensation, net of tax benefits	4,349	3,629	7,475
Depreciation and amortization of premises and equipment	21,768	20,420	18,592
(Gain) loss on sale and write-downs of other real estate owned, net	(105)	139	73
Deferred tax benefit	(9,095)	(6,863)	(356)
Amortization of core deposit intangibles	10,271	10,370	8,485
Amortization of investments in variable interest entities	13,457	11,282	9,700
Net decrease (increase) in accrued interest receivable	5,118	(17,663)	1,899
Net decrease (increase) in other assets	8,188	(20,926)	5,078
Net (decrease) increase in accrued interest payable	(1,222)	(1,507)	312
Net increase in other liabilities	588	5,840	254
Net cash provided by operating activities	572,049	189,545	226,649
Investing Activities
Sales of available-for-sale debt securities	0	0	712,113
Maturities, prepayments and calls of available-for-sale debt securities	1,453,049	758,879	711,838
Purchases of available-for-sale debt securities	(6,315,164)	(3,254,912)	(1,224,231)
Maturities, prepayments and calls of held-to-maturity debt securities	48,955	32,735	58,750
Purchases of held-to-maturity debt securities	(222,695)	0	0
Principal collected on loans	6,529,504	4,732,941	3,250,220
Loan originations	(7,000,632)	(5,864,038)	(3,623,548)
Net additions to premises and equipment	(9,436)	(11,717)	(16,398)
Proceeds from sale of other real estate owned	3,313	5,572	4,670
Proceeds from redemption of non-marketable equity securities	4,218	76,618	118,516
Purchases of non-marketable equity securities	(2)	(71,399)	(97,597)
Proceeds from bank-owned life insurance	2,112	0	0
Investments in variable interest entities	(22,640)	(12,088)	(16,348)
Net cash received from acquisitions	1,622,717	43,713	79,333
Net cash used in investing activities	(3,906,701)	(3,563,696)	(42,682)
Financing Activities
Net increase in deposits	3,266,304	3,418,199	285,856
Net increase in securities sold under agreements to repurchase	16,211	427,510	172,264
Net decrease in short-term Federal Home Loan Bank advances	0	(30,000)	(255,000)
Proceeds from long-term Federal Home Loan Bank advances	0	30,000	0
Repayments of long-term Federal Home Loan Bank advances	0	(38,589)	(151,160)
Net increase in other borrowed funds	3,526	564	14,109
Cash dividends paid	(145,557)	(131,263)	(124,468)
Tax withholding payments for stock-based compensation	(1,553)	(1,082)	(1,293)
Proceeds from stock option exercises	265	993	2,896
Net cash provided by (used in) financing activities	3,139,196	3,676,332	(56,796)
Net (decrease) increase in cash, cash equivalents and restricted cash	(195,456)	302,181	127,171
Cash, cash equivalents and restricted cash at beginning of period	633,142	330,961	203,790
Cash, cash equivalents and restricted cash at end of period	437,686	633,142	330,961
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest	19,779	28,822	42,461
Cash paid during the period for income taxes	67,306	63,021	36,817
Supplemental Disclosure of Non-Cash Investing Activities
Transfer of debt securities from held-to-maturity to available-for-sale	844,020	0	0
Sale and refinancing of other real estate owned	0	215	7
Transfer of loans to other real estate owned	1,482	2,076	2,349
Right-of-use assets obtained in exchange for operating lease liabilities	801	7,406	9,948
Dividends declared during the period but not paid	11,352	14,572	18,686
Acquisitions
Fair value of common stock shares issued	839,853	112,133	316,538
Cash consideration	9	13,721	16,424
Fair value of assets acquired	4,131,662	745,420	1,357,099
Liabilities assumed	$ 3,291,800	$ 619,566	$ 1,024,137