Consolidated Statements of Operations and Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
INTEREST AND DIVIDEND INCOME
Loan receivable	$ 473,782	$ 427,621	$ 390,440
Investment securities	21,426	21,523	24,237
Federal Home Loan Bank stock	2,099	3,164	1,974
Deposits with banks	1,763	1,398	1,996
Total interest and dividend income	499,070	453,706	418,647
INTEREST EXPENSE
Time deposits	43,327	39,443	35,111
Other deposits	16,094	12,445	10,658
Interest on securities sold under agreements to repurchase	15,329	15,813	24,685
Advances from the Federal Home Loan Bank	659	487	945
Long-term debt	5,791	5,776	4,467
Total interest expense	81,200	73,964	75,866
Net interest income before reversal for credit losses	417,870	379,742	342,781
Reversal for credit losses	(15,650)	(11,400)	(10,800)
Net interest income after reversal for credit losses	433,520	391,142	353,581
NON-INTEREST INCOME
Securities gains/(losses), net	4,898	(3,349)	6,748
Letters of credit commissions	4,939	5,545	6,043
Depository service fees	5,478	5,348	5,288
Other operating income	18,055	25,130	22,448
Total non-interest income	33,370	32,674	40,527
NON-INTEREST EXPENSE
Salaries and employee benefits	97,348	89,960	89,893
Occupancy expense	18,315	17,018	15,735
Computer and equipment expense	9,777	9,828	9,793
Professional services expense	18,686	17,316	15,927
Data processing service expense	8,957	7,698	6,707
FDIC and State assessments	9,712	9,087	8,796
Marketing expense	5,092	4,926	4,126
Other real estate owned income/(loss)	856	(800)	(1,304)
Operations of investments in affordable housing and alternative energy partnerships, net	40,264	33,335	6,990
Amortization of core deposit premium	689	667	719
Cost associated with debt redemption			3,348
Other operating expense	14,994	13,685	13,583
Total non-interest expense	224,690	202,720	174,313
Income before income tax expense	242,200	221,096	219,795
Income tax expense	67,101	59,987	81,965
Net income attributable to common stockholders	175,099	161,109	137,830
Other comprehensive income/(loss), net of tax:
Unrealized holding gains/(losses) on securities available for sale	6,725	(4,200)	30,468
Unrealized holding gains/(losses) on cash flow hedge derivatives	825	(598)	(2,397)
Less: reclassification adjustment for gains/(losses) included in net income	2,839	(1,941)	3,911
Total other comprehensive income/(loss), net of tax	4,711	(2,857)	24,160
Total comprehensive income	$ 179,810	$ 158,252	$ 161,990
Net income attributable to common stockholders per common share
Basic (in dollars per share)	$ 2.21	$ 2	$ 1.73
Diluted (in dollars per share)	$ 2.19	$ 1.98	$ 1.72
Basic average common shares outstanding (in shares)	79,153,762	80,563,577	79,661,571
Diluted average common shares outstanding (in shares)	79,929,262	81,294,796	80,106,895