Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 88,574	$ 71,932	$ 42,470
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of premises and equipment	8,363	8,706	6,303
Allocation of ESOP stock	1,575	1,618	919
Stock awards	3,861	3,038	2,181
Net excess tax benefit on stock compensation	(357)	(722)	(1,823)
Amortization of core deposit intangible	4,027	3,811	2,039
Net accretion of purchase accounting adjustments	(14,094)	(16,733)	(8,216)
Amortization of servicing asset	42	98	85
Net premium amortization in excess of discount accretion on securities	3,232	3,893	3,216
Net amortization of deferred costs on borrowings	216	262	74
Net amortization of deferred fees and discounts on loans	1,584	669	509
Provision for loan losses	1,636	3,490	4,445
Deferred tax provision (benefit)	16,053	(4,568)	35,440
Net loss on sale and write-down of other real estate owned	20	2,359	1,119
Write-down of fixed assets held for sale to net realizable value	7,532	4,024	6,084
Net (gain) loss on sale of fixed assets	(27)	(26)	150
Net unrealized (gain) loss on equity securities	(267)	199	0
Net gain on sales of loans	(16)	(668)	(100)
Proceeds from sales of mortgage loans held for sale	1,023	2,794	5,282
Mortgage loans originated for sale	(1,007)	(2,498)	(3,872)
Increase in value of Bank Owned Life Insurance	(5,420)	(5,105)	(3,299)
Net loss (gain) on sale of assets held for sale	17	(1,245)	0
(Increase) decrease in interest and dividends receivable	(397)	186	(2,265)
(Increase) decrease in other assets	(32,871)	27,301	(5,375)
Increase (decrease) in other liabilities	16,948	(10,264)	(5,235)
Total adjustments	11,673	20,619	37,661
Net cash provided by operating activities	100,247	92,551	80,131
Cash flows from investing activities:
Net (increase) decrease in loans receivable	(215,881)	103,889	(138,271)
Purchases of loans receivable	(101,674)	(199,580)	(37,337)
Proceeds from sale of under performing loans	5,901	10,412	11,186
Purchase of debt investment securities available-for-sale	(60,158)	(33,040)	(69,987)
Purchase of debt investment securities held-to-maturity	(4,381)	(6,486)	(125,324)
Purchase of debt mortgage-backed securities held-to-maturity	0	0	(165,501)
Purchase of equity investments	(214)	(191)	0
Principal repayments on debt mortgage-backed securities available-for-sale	503	655	0
Proceeds from maturities and calls of debt investment securities available-for-sale	29,299	18,501	0
Proceeds from maturities and calls of debt investment securities held-to-maturity	43,256	52,543	18,233
Principal repayments on debt mortgage-backed securities held-to-maturity	123,833	119,125	96,383
Proceeds from Bank Owned Life Insurance	870	2,708	624
Proceeds from the redemption of restricted equity investments	122,535	106,807	19,738
Purchases of restricted equity investments	(127,794)	(127,048)	(20,149)
Proceeds from sales of other real estate owned	2,060	5,438	3,880
Proceeds from sales of assets held for sale	2,353	10,050	0
Purchases of premises and equipment	(5,075)	(11,487)	(48,698)
Cash held in escrow for acquisitions	(46,950)
Cash consideration received (paid) for acquisition, net of cash received	59,395	(3,743)
Net cash (used in) provided by investing activities	(172,122)	48,553	(455,223)
Cash flows from financing activities:
Increase (decrease) in deposits	65,687	(143,025)	155,849
Increase in short-term borrowings	105,979	126,092	39,733
Proceeds from Federal Home Loan Bank advances	80,000	0	10,000
Repayments of Federal Home Loan Bank advances	(106,618)	(67,155)	(1,922)
Repayments of other borrowings	(263)	(439)
(Decrease) increase in advances by borrowers for taxes and insurance	(182)	2,910	(2,874)
Exercise of stock options	1,335	5,324	3,354
Payment of employee taxes withheld from stock awards	(2,858)	(3,295)	(1,522)
Purchase of treasury stock	(26,066)	(10,837)	0
Acquisition of common stock by ESOP	0	(8,400)	0
Dividends paid	(34,241)	(29,564)	(19,286)
Net cash provided by (used in) financing activities	82,773	(128,389)	183,332
Net increase (decrease) in cash and due from banks and restricted cash	10,898	12,715	(191,760)
Supplemental disclosure of cash flow information:
Cash and due from banks and restricted cash at beginning of year	122,328	109,613	301,373
Cash and due from banks at beginning of year	120,792	109,613	301,373
Restricted cash at beginning of year	1,536	0	0
Cash and due from banks at end of year	120,544	120,792	109,613
Restricted cash at end of year	12,682	1,536	0
Cash and due from banks and restricted cash at end of year	133,226	122,328	109,613
Cash paid during the year for:
Interest	52,315	36,447	20,219
Income taxes	20,006	2,317	6,008
Non cash Activities
Accretion of unrealized loss on securities reclassified to held-to-maturity	991	2,905	1,145
Net loan charge-offs	1,361	2,634	3,907
Transfer of premises and equipment to assets held-for-sale	2,189	11,092	5,729
Transfer of loans receivable to other real estate owned	963	992	3,726
Non-cash assets acquired:
Securities	103,775	254,522	0
Restricted equity investments	313	16,967	0
Loans	307,778	1,517,345	0
Premises and equipment	3,389	19,892	0
Accrued interest receivable	1,390	5,621	0
Bank Owned Life Insurance	10,460	85,238	0
Deferred tax asset	3,967	57,574	0
Other assets	1,278	6,343	0
Goodwill and other intangible assets, net	38,875	199,838	0
Total non-cash assets acquired	471,225	2,163,340	0
Liabilities assumed:
Deposits	449,018	1,616,073	0
Borrowings	0	127,727	0
Other liabilities	5,121	13,242	0
Total liabilities assumed	$ 454,139	$ 1,757,042	$ 0