Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Activities
Net income	$ 80,802	$ 43,339
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	48	19,185
Net amortization of debt securities	8,562	3,237
Net accretion of purchase accounting adjustments and deferred loan fees and costs	12,892	324
Origination of loans held for sale	(439,887)	(275,256)
Proceeds from loans held for sale	509,668	268,067
Gain on sale of loans	(21,624)	(11,862)
Gain on sale of debt securities	(284)	(863)
Bank-owned life insurance income, net	(641)	(656)
Stock-based compensation, net of tax benefits	1,491	1,199
Depreciation and amortization of premises and equipment	5,251	4,833
Gain loss on sale and write-downs of other real estate owned, net	0	(196)
Amortization of core deposit intangibles	2,488	2,533
Amortization of investments in variable interest entities	3,158	2,114
Net increase in accrued interest receivable	(3,834)	(10,690)
Net decrease (increase) in other assets	14,036	(9,793)
Net decrease in accrued interest payable	(715)	(99)
Net decrease in other liabilities	(23,666)	(9,654)
Net cash provided by operating activities	147,745	25,762
Investing Activities
Maturities, prepayments and calls of available-for-sale debt securities	290,743	176,926
Purchases of available-for-sale debt securities	(1,302,635)	(811,523)
Maturities, prepayments and calls of held-to-maturity debt securities	4,130	20,250
Principal collected on loans	1,519,493	810,652
Loan originations	(1,683,608)	(942,157)
Net additions to premises and equipment	(1,573)	(940)
Proceeds from sale of other real estate owned	176	1,198
Proceeds from redemption of non-marketable equity securities	0	36,244
Purchases of non-marketable equity securities	0	(51,598)
Proceeds from bank-owned life insurance	1,575	0
Investments in variable interest entities	(7,021)	(2,895)
Net cash received from acquisitions	0	43,713
Net cash used in investing activities	(1,178,720)	(720,130)
Financing Activities
Net increase in deposits	1,306,824	178,132
Net (decrease) increase in securities sold under agreements to repurchase	(7,705)	3,263
Net increase in short-term Federal Home Loan Bank advances	0	475,000
Repayments of long-term Federal Home Loan Bank advances	0	(547)
Net decrease in other borrowed funds	(7,116)	(5)
Cash dividends paid	(14,530)	(18,652)
Tax withholding payments for stock-based compensation	(1,351)	(977)
Proceeds from stock option exercises	161	634
Net cash provided by financing activities	1,276,283	636,848
Net increase (decrease) in cash, cash equivalents and restricted cash	245,308	(57,520)
Cash, cash equivalents and restricted cash at beginning of period	633,142	330,961
Cash, cash equivalents and restricted cash at end of period	878,450	273,441
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest	5,455	8,595
Cash paid during the period for income taxes	2	0
Supplemental Disclosure of Non-Cash Investing and Financing Activities
Transfer of debt securities from available-for-sale to held-to-maturity	403,767	0
Sale and refinancing of other real estate owned	0	215
Transfer of loans to other real estate owned	1,397	465
Right-of-use assets obtained in exchange for operating lease liabilities	345	2,241
Dividends declared during the period but not paid	29,674	27,727
Acquisitions
Fair value of common stock shares issued	0	112,133
Cash consideration	0	13,721
Fair value of assets acquired	0	744,109
Liabilities assumed	$ 0	$ 618,255