Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash Flows From Operating Activities
Net income	$ 51,210	$ 97,595
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	75,000	1,580
Stock-based compensation expense	4,909	4,528
Depreciation, amortization and accretion	10,382	17,298
Investment securities gain, net	16,674	2,132
Net realized gain on sale of premises and equipment and OPPO	705	666
Net realized loss (gain) on sale and valuation adjustments of OREO	(18)	507
Gain on bank owned life insurance death benefit	0	2,975
Originations of loans held for sale	217,017	68,722
Proceeds from sales of loans held for sale	205,932	60,382
Net change in:
Interest receivable	(12,310)	(1,555)
Interest payable	(219)	1,608
Other assets	(93,919)	(16,484)
Other liabilities	76,500	8,560
Net cash provided by operating activities	83,107	98,510
Cash Flows From Investing Activities
Loans originated, net of principal collected	(1,026,250)	(207,641)
Purchases of debt securities available for sale	(259,236)	(54,405)
Purchases of loans held for investment	0	49,039
Purchases of premises and equipment	(4,490)	(3,540)
Purchases of FHLB stock	(53,240)	(117,240)
Proceeds from sale of debt securities, available-for-sale	194,105	259,554
Proceeds from sale of equity securities	3,000	0
Proceeds from principal repayments and maturities of debt securities available for sale	265,072	182,125
Proceeds from sales of premises and equipment	932	24
Proceeds from redemption of Federal Home Loan Bank stock	85,080	113,400
Proceeds from sales of other real estate and other personal property owned	353	5,823
Proceeds from bank owned life insurance death benefit	1,050	0
Net cash provided by (used in) investing activities	(793,624)	129,061
Cash Flows From Financing Activities
Net increase (decrease) in deposits	2,446,782	(246,404)
Net decrease in sweep repurchase agreements	(12,958)	(10,868)
Proceeds from FHLB advances	1,331,000	2,931,000
Proceeds from FRB borrowings	222,010	36,000
Proceeds from other borrowings	9,222	100
Proceeds from exercise of stock options and employee stock purchase plan	945	893
Repayment of FHLB advances	(2,127,000)	(2,835,000)
Repayment of FRB borrowings	222,010	36,000
Repayments of other borrowings	9,222	100
Payments for common stock dividends	(55,750)	(61,511)
Purchase of treasury stock	(20,000)	(21,863)
Purchase and retirement of common stock	2,482	2,746
Net cash provided by (used in) financing activities	1,560,537	(246,499)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	850,020	(18,928)
Cash and cash equivalents at beginning of period	247,673	277,587
Cash and cash equivalents at end of period	1,097,693	258,659
Supplemental Information:
Cash paid for interest	13,075	16,564
Cash paid for income tax, net of refunds	21,501	20,940
Non-cash investing and financing activities
Loans transferred to OREO	558	386
Premises and equipment expenditures incurred but not yet paid	9	56
Change in dividends payable on unvested shares included in other liabilities	$ 296	$ 145