CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net income/(loss) from continuing operations	$ 118,664,000	$ (513,175,000)	$ 101,521,000
Net (loss) from discontinued operations	0	(19,842,000)	(4,071,000)
Net income/(loss)	118,664,000	(533,017,000)	97,450,000
Adjustments to reconcile net income to net cash provided by operating activities:
Provision (benefit) for credit losses	(500,000)	75,878,000	35,419,000
Net amortization of securities	1,939,000	2,513,000	2,407,000
Change in unamortized net loan origination costs and premiums	(1,918,000)	21,856,000	12,759,000
Premises and equipment depreciation and amortization expense	11,035,000	11,919,000	10,921,000
Stock-based compensation expense	4,170,000	4,727,000	4,812,000
Accretion of purchase accounting entries, net	(6,577,000)	(10,377,000)	(14,813,000)
Amortization of other intangibles	5,200,000	6,181,000	5,783,000
Income from cash surrender value of bank-owned life insurance policies	(5,561,000)	(5,354,000)	(5,349,000)
Securities losses/(gains), net	787,000	7,576,000	(4,389,000)
Net change in loans held-for-sale	5,775,000	(4,267,000)	(5,137,000)
Loss on disposition of assets	2,811,000	327,000	3,443,000
Loss on sale of real estate	6,000	13,000	5,000
Amortization of interest in tax-advantaged projects	3,444,000	3,645,000	6,455,000
Goodwill impairment	0	553,762,000	0
Gain on sale of business operations and other assets	(52,942,000)	0	0
Prepayment penalties on repayment of Federal Home Loan Bank advances	862,000	0	0
Net change in other	18,282,000	(31,247,000)	(23,418,000)
Net cash provided by operating activities of continuing operations	105,477,000	123,977,000	130,419,000
Net cash provided/(used) by operating activities of discontinued operations	0	103,664,000	(18,894,000)
Net cash provided by operating activities	105,477,000	227,641,000	111,525,000
Cash flows from investing activities:
Net decrease in trading security	776,000	734,000	701,000
Purchases of marketable equity securities	0	(17,631,000)	(23,841,000)
Proceeds from sales of marketable equity securities	2,880,000	33,928,000	43,075,000
Purchases of securities available for sale	(804,616,000)	(885,182,000)	(119,671,000)
Proceeds from sales of securities available for sale	0	69,337,000	136,229,000
Proceeds from maturities, calls, and prepayments of securities available for sale	575,538,000	457,586,000	240,586,000
Purchases of securities held to maturity	(219,470,000)	(144,651,000)	(7,260,000)
Proceeds from maturities, calls, and prepayments of securities held to maturity	46,061,000	35,331,000	21,602,000
Net change in loans	1,262,521,000	1,054,029,000	694,657,000
Net change in Mid-Atlantic region loans held for sale	50,914,000	0	0
Acquisitions, net of cash paid	0	0	110,774,000
Proceeds from surrender of bank-owned life insurance	2,566,000	553,000	2,451,000
Purchase of Federal Home Loan Bank stock	0	(6,741,000)	(112,208,000)
Proceeds from sales of Federal Home Loan Bank stock	24,078,000	19,887,000	149,455,000
Net investment in limited partnership tax credits	(2,878,000)	(7,280,000)	(4,387,000)
Purchase of premises and equipment, net	(1,606,000)	(7,208,000)	(10,565,000)
Proceeds from sales of seasoned commercial loan portfolios	16,417,000	37,988,000	81,147,000
Proceeds from sales of other real estate owned	187,000	171,000	150,000
Cash outflows from sale of business operations and other assets	(352,814,000)	0	0
Net investing cash flows provided/(used) by discontinued operations	0	252,000	(313,000)
Net cash provided by investing activities	600,554,000	641,103,000	1,202,582,000
Cash flows from financing activities:
Net increase in deposits	(154,052,000)	499,657,000	23,996,000
Net change in Mid-Atlantic region deposits held for sale	20,953,000	0	0
Proceeds from Federal Home Loan Bank advances and other borrowings	0	326,277,000	5,384,982,000
Repayments of Federal Home Loan Bank advances and other borrowings	(462,059,000)	(582,648,000)	(6,228,780,000)
Purchase of treasury stock	(68,712,000)	(473,000)	(52,746,000)
Exercise of stock options	417,000	664,000	188,000
Common and preferred stock cash dividends paid	(24,553,000)	(36,564,000)	(45,107,000)
Settlement of derivative contracts with financial institution counterparties	51,907,000	(97,611,000)	0
Net cash (used)/provided by financing activities	(636,099,000)	109,302,000	(917,467,000)
Net change in cash and cash equivalents	69,932,000	978,046,000	396,640,000
Cash and cash equivalents at beginning of year	1,557,875,000	579,829,000	183,189,000
Cash and cash equivalents at end of year	1,627,807,000	1,557,875,000	579,829,000
Supplemental cash flow information:
Interest paid on deposits	29,606,000	82,319,000	119,695,000
Interest paid on borrowed funds	11,385,000	21,277,000	33,406,000
Income taxes (refunded)/paid, net	14,816,000	(13,864,000)	19,818,000
Acquisition of non-cash assets and liabilities:
Assets acquired	0	0	1,595,054,000
Liabilities assumed	0	0	(1,530,010,000)
Other net comprehensive income/(loss)	(34,114,000)	18,878,000	25,463,000
Reclassifications of loans to loans held for sale	11,660,000	14,845,000	120,307,000
Reclass of premises and equipment to held-for-sale	4,577,000	0	0
Real estate owned acquired in settlement of loans	0	224,000	0
Retained earnings
Cash flows from operating activities:
Net income/(loss)	118,664,000	(533,017,000)	97,450,000
Impact of ASC 326 adoption | Retained earnings
Impact to retained earnings from adoption of ASC 326, net of tax	0	24,380,000	0
Discontinued Operations, Held-for-sale | Mid-Atlantic Branch Sale
Reclassifications of loans to loans held for sale	0	317,304,000	0
Mid- Atlantic liabilities reclassified to held for sale	0	630,065,000	0
Reclass of Mid-Atlantic loans held-for-sale to portfolio loans, net	29,418,000	0	0
Reclass of Mid-Atlantic deposits held-for-sale to deposits, net	$ 7,197,000	$ 0	$ 0