Consolidated Statements of Operations and Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
INTEREST AND DIVIDEND INCOME
Loan receivable		$ 652,480	$ 549,291	$ 473,782
Investment securities		28,603	20,531	21,426
Federal Home Loan Bank stock		1,663	1,798	2,099
Federal funds sold and securities purchased under agreement to resell			110
Deposits with banks		5,209	4,421	1,763
Total interest and dividend income		687,955	576,151	499,070
INTEREST EXPENSE
Time deposits		86,368	46,768	43,327
Other deposits		20,503	19,076	16,094
Interest on securities sold under agreements to repurchase		1,446	4,250	15,329
Advances from the Federal Home Loan Bank		3,739	2,712	659
Long-term debt		8,723	5,775	5,791
Deferred payments from acquisition		1,090	1,861
Short-term borrowings		187
Total interest expense		122,056	80,442	81,200
Net interest income before reversal for credit losses		565,899	495,709	417,870
Reversal for credit losses		(4,500)	(2,500)	(15,650)
Net interest income after reversal for credit losses		570,399	498,209	433,520
NON-INTEREST INCOME
Net (losses)/gains from equity securities,		(2,787)
Securities gains, net		22	1,006	4,898
Letters of credit commissions		5,614	4,860	4,939
Depository service fees		27,985	25,649	25,486
Gain from acquisition		340	5,628
Other operating income		23,434	19,179	18,055
Total non-interest income	[1]	31,707	36,297	33,370
NON-INTEREST EXPENSE
Salaries and employee benefits		124,477	109,458	97,348
Occupancy expense		20,690	20,429	18,315
Computer and equipment expense		11,402	10,846	9,777
Professional services expense		22,810	20,439	18,686
Data processing service expense		12,438	11,190	8,957
FDIC and State assessments		8,000	10,633	9,712
Marketing expense		7,837	6,200	5,092
Other real estate owned (income)/loss		(719)	(1,649)	856
Operations of investments in affordable housing and alternative energy partnerships, net		40,515	27,212	40,264
Amortization of core deposit premium		876	930	689
Acquisition and integration costs		2,105	4,121
Other operating expense		13,988	16,390	14,994
Total non-interest expense		264,419	236,199	224,690
Income before income tax expense		337,687	298,307	242,200
Total income tax expense, amount		65,802	122,265	67,101
Net income attributable to common stockholders		271,885	176,042	175,099
Other comprehensive income/(loss), net of tax:
Unrealized holding (losses)/gains on securities available for sale		(7,934)	1,068	6,725
Unrealized holding gains on cash flow hedge derivatives		1,525	719	825
Less: reclassification adjustment for gains included in net income		15	583	2,839
Total other comprehensive (loss)/income, net of tax		(6,424)	1,204	4,711
Total comprehensive income		$ 265,461	$ 177,246	$ 179,810
Net income attributable to common stockholders per common share
Basic (in dollars per share)		$ 3.35	$ 2.19	$ 2.21
Diluted (in dollars per share)		$ 3.33	$ 2.17	$ 2.19
Basic average common shares outstanding (in shares)		81,131,269	80,262,782	79,153,762
Diluted average common shares outstanding (in shares)		81,607,346	81,004,550	79,929,262
Deposit Account [Member]
NON-INTEREST INCOME
Depository service fees		$ 5,084	$ 5,624	$ 5,478

[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 prior period amounts to conform to the periods presentation.