Investment Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Available-for-sale Securities [Abstract]
Amortized Cost	$ 386,862	$ 398,815	[1]
Gross Unrealized Gains	1,722	920
Gross Unrealized Losses	2,590	9,301
Total	385,994	390,434	[1]
Held-to-maturity Securities [Abstract]
Amortized Cost	145,127	147,967
Gross Unrealized Gains	867	0
Gross Unrealized Losses	141	2,782
Total	145,853	145,185	[1]
Amortized Cost, Total	531,989	546,782
Gross Unrealized Gains, Total	2,589	920
Gross Unrealized Losses, Total	2,731	12,083
Estimated Fair Value, Total	531,847	535,619
U.S. Government-sponsored agencies [Member]
Available-for-sale Securities [Abstract]
Amortized Cost		2,005
Gross Unrealized Gains		3
Gross Unrealized Losses		0
Total		2,008
Residential mortgage-backed securities - GSE [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	278,521	286,057
Gross Unrealized Gains	920	339
Gross Unrealized Losses	2,379	8,289
Total	277,062	278,107
Held-to-maturity Securities [Abstract]
Amortized Cost	118,194	120,197
Gross Unrealized Gains	698	0
Gross Unrealized Losses	109	2,310
Total	118,783	117,887
Residential mortgage-backed securities - Private [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	31,079	33,235
Gross Unrealized Gains	399	578
Gross Unrealized Losses	44	236
Total	31,434	33,577
Held-to-maturity Securities [Abstract]
Amortized Cost	16,877	17,712
Gross Unrealized Gains	0	0
Gross Unrealized Losses	32	298
Total	16,845	17,414
Commercial mortgage-backed securities - GSE [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	21,880	21,980
Gross Unrealized Gains	242	0
Gross Unrealized Losses	0	368
Total	22,122	21,612
Commercial mortgage-backed securities - Private [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	17,858	17,869
Gross Unrealized Gains	140	0
Gross Unrealized Losses	150	294
Total	17,848	17,575
Held-to-maturity Securities [Abstract]
Amortized Cost	10,056	10,058
Gross Unrealized Gains	169	0
Gross Unrealized Losses	0	174
Total	10,225	9,884
Corporate notes [Member]
Available-for-sale Securities [Abstract]
Amortized Cost	37,524	37,669
Gross Unrealized Gains	21	0
Gross Unrealized Losses	17	114
Total	$ 37,528	$ 37,555

[1] Derived from audited consolidated financial statements