CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Cash flows from operating activities:
Net (loss)/income from continuing operations	$ 23,043	$ 20,659	$ (532,074)	$ 68,885
Net (loss)/income from discontinued operations	(1,818)	1,957	(15,952)	2,814
Net income/(loss)	21,225	22,616	(548,026)	71,699
Adjustments to reconcile net (loss)/income to net cash provided by operating activities:
Provision for credit losses	1,200	22,600	65,878	30,068
Net amortization of securities			2,035	1,811
Change in unamortized net loan costs and premiums			20,565	8,964
Premises and equipment depreciation and amortization expense			8,944	7,844
Stock-based compensation expense			3,450	3,546
Accretion of purchase accounting entries, net			(8,146)	(9,589)
Amortization of other intangibles	1,530	1,526	4,668	4,201
Income from cash surrender value of bank-owned life insurance policies			(3,876)	(3,546)
Securities losses (gains), net			9,925	(2,655)
Net change in loans held-for-sale			(7,130)	(2,920)
Decrease in right-of-use lease assets			1,809	10,025
Decrease in lease liabilities			(1,746)	(10,189)
Loss on disposition of assets			327	1,615
Loss on sale of real estate			13	5
Amortization of interest in tax-advantaged projects			2,621	4,459
Goodwill impairment	0	0	553,762	0
Net change in other			(36,152)	(4,803)
Net cash provided by operating activities of continuing operations			84,873	107,721
Net cash provided (used) by operating activities of discontinued operations			109,897	(104,001)
Net cash provided by operating activities			194,770	3,720
Cash flows from investing activities:
Net decrease in trading security			546	522
Purchases of marketable equity securities			(17,631)	(18,150)
Proceeds from sales of marketable equity securities			18,458	17,728
Purchases of securities available for sale	(319,200)	(14,900)	(635,194)	(30,032)
Proceeds from sales of securities available for sale	64,200	0	71,844	82,978
Proceeds from maturities, calls, and prepayments of securities available for sale			320,010	151,155
Purchases of securities held to maturity			(3,200)	(5,692)
Proceeds from maturities, calls, and prepayments of securities held to maturity			29,237	13,822
Net change in loans			474,707	395,643
Proceeds from surrender of bank-owned life insurance			553	1,457
Purchase of Federal Home Loan Bank stock			(6,741)	(112,208)
Proceeds from redemption of Federal Home Loan Bank stock			14,240	141,424
Net investment in limited partnership tax credits			(6,499)	(3,997)
Purchase of premises and equipment, net			(6,190)	(8,518)
Acquisitions, net of cash acquired			0	110,774
Proceeds from sales of seasoned commercial loan portfolios			37,988	0
Proceeds from sale of other real estate			171	150
Net investing cash flows from discontinued operations			0	(2)
Net cash provided by investing activities			292,299	737,054
Cash flows from financing activities:
Net increase in deposits			133,031	109,238
Proceeds from Federal Home Loan Bank advances and other borrowings			326,277	5,267,520
Repayments of Federal Home Loan Bank advances and other borrowings			(451,493)	(5,937,568)
Purchase of treasury stock			(473)	(27,651)
Exercise of stock options			607	69
Common and preferred stock cash dividends paid			(30,456)	(33,476)
Settlement of derivative contracts with financial institution counterparties			(109,099)	0
Net cash used by financing activities			(131,606)	(621,868)
Net change in cash and cash equivalents			355,463	118,906
Cash and cash equivalents at beginning of period			579,829	183,189	$ 183,189
Cash and cash equivalents at end of period	935,292	302,095	935,292	302,095	579,829
Supplemental cash flow information:
Interest paid on deposits			67,119	87,499
Interest paid on borrowed funds			16,961	27,499
Income taxes paid, net			345	8,368
Assets acquired			0	1,595,054
Liabilities assumed			0	(1,530,010)
Other non-cash changes:
Other net comprehensive income	(813)	4,579	20,433	29,350
Total shareholders’ equity	(1,179,025)	(1,772,224)	(1,179,025)	(1,772,224)	$ (1,758,564)
Reclass of seasoned loan portfolios to held-for-sale, net			10,048	0
Real estate owned acquired in settlement of loans			224	0
Accounting standards update					us-gaap:AccountingStandardsUpdate201613Member
Cumulative Effect, Period of Adoption, Adjustment
Other non-cash changes:
Total shareholders’ equity					$ 24,380
Retained earnings (deficit)
Cash flows from operating activities:
Net income/(loss)	21,225	22,616	(548,026)	71,699
Other non-cash changes:
Total shareholders’ equity	$ 242,175	$ (346,971)	$ 242,175	$ (346,971)	(361,082)
Retained earnings (deficit) | Cumulative Effect, Period of Adoption, Adjustment
Other non-cash changes:
Total shareholders’ equity					$ 24,380