Investment Securities - Schedule of Debt Securities Expected Maturity (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Amortized Cost
Due within 1 year		$ 0
Due after 1 but within 5 years		2,636
Due after 5 but within 10 years		31,893
Due after 10 years		4,138
Amortized Cost		38,667
Held-to-maturity Securities		372,513	$ 384,324
Estimated Fair Value
Due within 1 year		0
Due after 1 but within 5 years		2,615
Due after 5 but within 10 years		31,384
Due after 10 years		4,002
Estimated Fair Value		38,001
Securities held to maturity, fair value		368,618	$ 382,341
Mortgage-Backed Securities [Member]
Amortized Cost
Held-to-maturity Securities	[1]	333,846
Estimated Fair Value
Securities held to maturity, fair value	[1]	330,617
Mortgage-Backed Securities [Member] | US Government Agencies Debt Securities [Member]
Amortized Cost
Held-to-maturity Securities		38,700
Estimated Fair Value
Securities held to maturity, fair value		38,200
Mortgage-Backed Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Amortized Cost
Held-to-maturity Securities		295,100
Estimated Fair Value
Securities held to maturity, fair value		$ 292,400

[1] Mortgage Backed Securities include an amortized cost of $38.7 million and a fair value of $38.2 million for Obligations of U.S. Government agencies issued by Ginnie Mae and an amortized cost of $295.1 million and a fair value of $292.4 million for Obligations of U.S. Government-sponsored enterprises issued by Fannie Mae and Freddie Mac.