Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating Activities
Net income	$ 234,048	$ 184,540
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	(4,880)	41,300
Net amortization of debt securities	32,934	10,830
Net amortization of purchase accounting adjustments and deferred loan fees and costs	(1,003)	(23,369)
Origination of loans held for sale	(1,184,305)	(1,393,224)
Proceeds from loans held for sale	1,372,592	1,400,697
Gain on sale of loans	(51,632)	(73,236)
Gain on sale of debt securities	(55)	(1,015)
Bank-owned life insurance income, net	(2,027)	(2,059)
Stock-based compensation, net of tax benefits	3,440	2,829
Depreciation and amortization of premises and equipment	15,593	15,124
Gain on sale and write-downs of other real estate owned, net	(127)	(64)
Amortization of core deposit intangibles	7,464	7,758
Amortization of investments in variable interest entities	9,520	8,244
Net increase in accrued interest receivable	(4,201)	(33,558)
Net increase in other assets	(5,430)	(22,729)
Net decrease in accrued interest payable	(868)	(861)
Net decrease in other liabilities	(3,753)	(7,450)
Net cash provided by operating activities	417,310	113,757
Investing Activities
Maturities, prepayments and calls of available-for-sale debt securities	1,026,010	545,191
Purchases of available-for-sale debt securities	(4,035,869)	(1,839,308)
Maturities, prepayments and calls of held-to-maturity debt securities	25,480	29,530
Purchases of held-to-maturity debt securities	(125,527)	0
Principal collected on loans	4,825,177	2,978,796
Loan originations	(5,062,750)	(4,627,653)
Net additions to premises and equipment	(4,187)	(8,140)
Proceeds from sale of other real estate owned	3,246	2,140
Proceeds from redemption of non-marketable equity securities	180	76,275
Purchases of non-marketable equity securities	(2)	(71,397)
Proceeds from bank-owned life insurance	2,112	0
Investments in variable interest entities	(14,799)	(7,975)
Net cash received from acquisitions	0	43,713
Net cash used in investing activities	(3,360,929)	(2,878,828)
Financing Activities
Net increase in deposits	2,705,870	2,920,429
Net increase in securities sold under agreements to repurchase	36,356	388,595
Net decrease in short-term Federal Home Loan Bank advances	0	(30,000)
Proceeds from long-term Federal Home Loan Bank advances	0	30,000
Repayments of long-term Federal Home Loan Bank advances	0	(31,271)
Net (increase) decrease in other borrowed funds	(6,897)	463
Cash dividends paid	(74,709)	(73,999)
Tax withholding payments for stock-based compensation	(1,520)	(1,023)
Proceeds from stock option exercises	265	795
Net cash provided by financing activities	2,659,365	3,203,989
Net (decrease) increase in cash, cash equivalents and restricted cash	(284,254)	438,918
Cash, cash equivalents and restricted cash at beginning of period	633,142	330,961
Cash, cash equivalents and restricted cash at end of period	348,888	769,879
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest	14,223	22,626
Cash paid during the period for income taxes	58,645	43,944
Supplemental Disclosure of Non-Cash Investing and Financing Activities
Transfer of debt securities from available-for-sale to held-to-maturity	844,020	0
Sale and refinancing of other real estate owned	0	215
Transfer of loans to other real estate owned	1,481	2,062
Right-of-use assets obtained in exchange for operating lease liabilities	801	7,343
Dividends declared during the period but not paid	30,761	28,799
Acquisitions
Fair value of common stock shares issued	0	112,133
Cash consideration	0	13,721
Fair value of assets acquired	0	745,420
Liabilities assumed	$ 0	$ 619,565