INVESTMENT AND MORTGAGE-BACKED SECURITIES, Continuous Unrealized Loss Position (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 Security	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Investment securities available-for-sale, Unrealized Losses [Abstract]
Number of TRUP securities with unrealized holding losses | Security	2
Number of TRUP securities not deemed having OTTI | Security	1
Number of TRUP securities deemed have OTTI | Security	1
Agency Notes [Member]
Debt securities available-for-sale, Fair Value [Abstract]
Less than 12 Consecutive Months		$ 5,100
12 Consecutive Months or Longer		0
Total		5,100
Debt securities available-for-sale, Unrealized Losses [Abstract]
Less than 12 Consecutive Months		10
12 Consecutive Months or Longer		0
Total		10
Registered Mutual Funds [Member]
Investment securities available-for-sale, Fair Value [Abstract]
Less than 12 Consecutive Months			$ 0
12 Consecutive Months or Longer			2,591
Total			2,591
Investment securities available-for-sale, Unrealized Losses [Abstract]
Less than 12 Consecutive Months			0
12 Consecutive Months or Longer			84
Total			84
Corporate Securities [Member]
Debt securities available-for-sale, Fair Value [Abstract]
Less than 12 Consecutive Months		11,135
12 Consecutive Months or Longer		0
Total		11,135
Debt securities available-for-sale, Unrealized Losses [Abstract]
Less than 12 Consecutive Months		32
12 Consecutive Months or Longer		0
Total		32
Pass through MBS issued by GSEs [Member]
Debt securities available-for-sale, Fair Value [Abstract]
Less than 12 Consecutive Months		216,451
12 Consecutive Months or Longer		45,489
Total		261,940
Debt securities available-for-sale, Unrealized Losses [Abstract]
Less than 12 Consecutive Months		1,049
12 Consecutive Months or Longer		951
Total		2,000
Investment securities available-for-sale, Fair Value [Abstract]
Less than 12 Consecutive Months			55,819
12 Consecutive Months or Longer			0
Total			55,819
Investment securities available-for-sale, Unrealized Losses [Abstract]
Less than 12 Consecutive Months			325
12 Consecutive Months or Longer			0
Total			325
Agency CMO [Member]
Debt securities available-for-sale, Fair Value [Abstract]
Less than 12 Consecutive Months		52,605
12 Consecutive Months or Longer		39,833
Total		92,438
Debt securities available-for-sale, Unrealized Losses [Abstract]
Less than 12 Consecutive Months		439
12 Consecutive Months or Longer		1,196
Total		$ 1,635
Investment securities available-for-sale, Fair Value [Abstract]
Less than 12 Consecutive Months			86,746
12 Consecutive Months or Longer			3,168
Total			89,914
Investment securities available-for-sale, Unrealized Losses [Abstract]
Less than 12 Consecutive Months			96
12 Consecutive Months or Longer			69
Total			$ 165