Investment Securities - Schedule of Gross Unrealized Losses (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Schedule Of Available For Sale Securities [Line Items]
Fair Value, Less than 12 months	$ 39,887	$ 240,128
Unrealized Loss, Less than 12 months	142	1,924
Fair Value, 12 months or more	21,916	140,866
Unrealized Loss, 12 months or more	248	3,984
Fair Value, Total	61,803	380,994
Unrealized Losses, Total	390	5,908
Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Fair Value, Less than 12 months	39,887	240,128
Unrealized Loss, Less than 12 months	142	1,924
Fair Value, 12 months or more	20,373	139,283
Unrealized Loss, 12 months or more	174	3,894
Fair Value, Total	60,260	379,411
Unrealized Losses, Total	316	5,818
Debt Securities | U.S. Government Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Fair Value, Less than 12 months		15,887
Unrealized Loss, Less than 12 months		124
Fair Value, 12 months or more		17,921
Unrealized Loss, 12 months or more		229
Fair Value, Total		33,808
Unrealized Losses, Total		353
Debt Securities | Mortgage-backed Securities - Residential
Schedule Of Available For Sale Securities [Line Items]
Fair Value, Less than 12 months	35,601	219,756
Unrealized Loss, Less than 12 months	96	1,778
Fair Value, 12 months or more	20,373	121,362
Unrealized Loss, 12 months or more	174	3,665
Fair Value, Total	55,974	341,118
Unrealized Losses, Total	270	5,443
Debt Securities | Municipals, Tax Exempt
Schedule Of Available For Sale Securities [Line Items]
Fair Value, Less than 12 months	4,286	4,485
Unrealized Loss, Less than 12 months	46	22
Fair Value, Total	4,286	4,485
Unrealized Losses, Total	46	22
Equity Securities
Schedule Of Available For Sale Securities [Line Items]
Fair Value, 12 months or more	1,543	1,583
Unrealized Loss, 12 months or more	74	90
Fair Value, Total	1,543	1,583
Unrealized Losses, Total	$ 74	$ 90