CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
INTEREST INCOME:
Loans receivable	$ 471,473	$ 413,370	$ 374,449
Mortgage-backed securities	38,640	35,076	24,535
Securities and cash equivalents	15,566	15,186	13,300
Total interest income	525,679	463,632	412,284
INTEREST EXPENSE:
Deposits	37,630	20,642	12,273
FHLB advances	12,234	5,636	1,908
Other borrowings	330	245	317
Junior subordinated debentures	6,574	6,136	4,752
Total interest expense	56,768	32,659	19,250
Net interest income before provision for loan losses	468,911	430,973	393,034
PROVISION FOR LOAN LOSSES	10,000	8,500	8,000
Net interest income	458,911	422,473	385,034
NON-INTEREST INCOME
Total Deposit Fees and Other Service Charges	46,632	48,074	43,452
Bank Owned Life Insurance Income	4,645	4,505	4,618
Miscellaneous	8,632	7,148	8,985
Other operating income	82,124	81,070	77,935
Net gain (loss) on sale of securities	33	(837)	(2,080)
Net change in valuation of financial instruments carried at fair value	(208)	3,775	(2,844)
Gain on sale of branches, including related loans and deposits	0	0	12,189
Total non-interest income	81,949	84,008	85,200
NON-INTEREST EXPENSE:
Income before provision for income taxes	183,132	165,110	151,264
PROVISION FOR INCOME TAXES	36,854	28,595	90,488
NET INCOME	146,278	136,515	60,776
Salary and employee benefits	226,409	202,613	192,096
Less capitalized loan origination costs	(28,934)	(17,925)	(17,379)
Occupancy and equipment	52,390	49,215	47,866
Information/computer data services	22,458	18,823	17,245
Payment and card processing expenses	16,993	15,412	14,330
Professional and legal expenses	9,736	17,945	17,534
Advertising and marketing	7,836	8,346	8,637
Deposit insurance	2,840	4,446	4,689
State/municipal business and use taxes	3,880	3,284	2,594
REO operations	303	804	(2,030)
Amortization of core deposit intangibles	8,151	6,047	6,246
Miscellaneous	28,122	26,754	27,142
Total other operating expense, before acquisition related costs	350,184	335,764	318,970
Acquisition related costs	7,544	5,607	0
Total non-interest expense	$ 357,728	$ 341,371	$ 318,970
Earnings per common share
Basic (in dollars per share)	$ 4.20	$ 4.16	$ 1.85
Diluted (in dollars per share)	4.18	4.15	1.84
Cumulative dividends declared per common share (in dollars per share)	$ 2.64	$ 1.96	$ 2.00
Weighted average number of common shares outstanding:
Basic	34,868,434	32,784,724	32,888,007
Diluted	34,967,684	32,894,425	32,986,707
Mortgage Banking [Member]
NON-INTEREST INCOME
Fees and Commissions, Mortgage Banking and Servicing	$ 22,215	$ 21,343	$ 20,880