Consolidated Statements of Operations and Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
INTEREST AND DIVIDEND INCOME
Loan receivable		$ 729,619	$ 652,480	$ 549,291
Investment securities		33,037	28,603	20,531
Federal Home Loan Bank stock		1,207	1,663	1,798
Federal funds sold and securities purchased under agreement to resell		0	0	110
Deposits with banks		5,404	5,209	4,421
Total interest and dividend income		769,267	687,955	576,151
INTEREST EXPENSE
Time deposits		152,791	86,368	46,768
Other deposits		25,311	20,503	19,076
Interest on securities sold under agreements to repurchase		0	1,446	4,250
Advances from the Federal Home Loan Bank		7,441	3,739	2,712
Long-term debt		7,847	8,723	5,775
Deferred payments from acquisition		568	1,090	1,861
Short-term borrowings		403	187	0
Total interest expense		194,361	122,056	80,442
Net interest income before reversal for credit losses		574,906	565,899	495,709
Reversal for credit losses		(7,000)	(4,500)	(2,500)
Net interest income after reversal for credit losses		581,906	570,399	498,209
NON-INTEREST INCOME
Net gains/(losses) from equity securities		5,736	(2,787)	0
Securities gains, net		211	22	1,006
Letters of credit commissions		6,407	5,614	4,860
Depository service fees		31,481	27,985	25,649
Gain from acquisition.		0	340	5,628
Other operating income		27,634	23,434	19,179
Total non-interest income	[1]	44,751	31,707	36,297
NON-INTEREST EXPENSE
Salaries and employee benefits		129,300	124,477	109,458
Occupancy expense		22,004	20,690	20,429
Computer and equipment expense		11,113	11,402	10,846
Professional services expense		23,107	22,810	20,439
Data processing service expense		13,210	12,438	11,190
FDIC and State assessments		9,617	8,000	10,633
Marketing expense		7,585	7,837	6,200
Other real estate owned loss/(income)		1,115	(719)	(1,649)
Operations of investments in affordable housing and alternative energy partnerships, net		39,731	40,515	27,212
Amortization of core deposit premium		687	876	930
Acquisition and integration costs		0	2,105	4,121
Other operating expense		19,819	13,988	16,390
Total non-interest expense		277,288	264,419	236,199
Income before income tax		349,369	337,687	298,307
Income tax expense		70,234	65,802	122,265
Net income attributable to common stockholders		279,135	271,885	176,042
Other comprehensive income/(loss), net of tax:
Unrealized holding gains/(losses) on securities available for sale		23,628	(7,934)	1,068
Unrealized holding (losses)/gains on cash flow hedge derivatives		(3,171)	1,525	719
Less: reclassification adjustment for gains included in net income		149	15	583
Total other comprehensive income/(loss), net of tax		20,308	(6,424)	1,204
Total comprehensive income		$ 299,443	$ 265,461	$ 177,246
Net income attributable to common stockholders per common share
Basic (in dollars per share)		$ 3.49	$ 3.35	$ 2.19
Diluted (in dollars per share)		$ 3.48	$ 3.33	$ 2.17
Basic average common shares outstanding (in shares)		79,999,703	81,131,269	80,262,782
Diluted average common shares outstanding (in shares)		80,247,893	81,607,346	81,004,550
Deposit Account [Member]
NON-INTEREST INCOME
Depository service fees		$ 4,763	$ 5,084	$ 5,624

[1] There were no adjustments to the Company's financial statements recorded as a result of the adoption of ASC 606. For comparability, the Company has adjusted consolidated prior period amounts to conform to the periods presentation.