SECURITIES - Summary of Available for Sale Investment Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Available for sale:
Amortized Cost	$ 645,573	$ 697,381
Gross Unrealized Gains	3,881	969
Gross Unrealized Losses	(6,557)	(17,464)
Estimated Fair Value	642,897	680,886
U.S. GSE securities
Available for sale:
Amortized Cost	15,000	29,997
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(37)	(947)
Estimated Fair Value	14,963	29,050
State and municipal obligations
Available for sale:
Amortized Cost	28,108	40,980
Gross Unrealized Gains	641	105
Gross Unrealized Losses	(1)	(354)
Estimated Fair Value	28,748	40,731
U.S. GSE residential mortgage-backed securities
Available for sale:
Amortized Cost	93,898	96,536
Gross Unrealized Gains	268	38
Gross Unrealized Losses	(909)	(3,036)
Estimated Fair Value	93,257	93,538
U.S. GSE residential collateralized mortgage obligations
Available for sale:
Amortized Cost	333,584	362,905
Gross Unrealized Gains	1,628	826
Gross Unrealized Losses	(1,428)	(5,954)
Estimated Fair Value	333,784	357,777
U.S. GSE commercial mortgage-backed securities
Available for sale:
Amortized Cost	7,013	3,536
Gross Unrealized Gains	38	0
Gross Unrealized Losses	0	(28)
Estimated Fair Value	7,051	3,508
U.S. GSE commercial collateralized mortgage obligations
Available for sale:
Amortized Cost	97,720	93,177
Gross Unrealized Gains	1,306	0
Gross Unrealized Losses	(629)	(2,539)
Estimated Fair Value	98,397	90,638
Other asset backed securities
Available for sale:
Amortized Cost	24,250	24,250
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(788)	(1,031)
Estimated Fair Value	23,462	23,219
Corporate bonds
Available for sale:
Amortized Cost	46,000	46,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2,765)	(3,575)
Estimated Fair Value	$ 43,235	$ 42,425

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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