Investment Securities Schedule of Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Due within 1 year	$ 0
Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	4,525	$ 331
Held-to-maturity Securities	396,444	384,324
Securities held to maturity, fair value	400,964	$ 382,341
Due after 1 but within 5 years	107
Due after 5 but within 10 years	27,839
Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value	28,412
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value	108
Due after 10 years	5,947
Held-to-maturity Securities, Debt Maturities, after Ten Years, Fair Value	5,998
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis	33,893
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value	34,518
Held-to-maturity Securities, Debt Maturities, without Single Maturity Date, Net Carrying Amount	362,551
Held-to-maturity Securities, Debt Maturities, without Single Maturity Date, Fair Value	366,446
US Government Agencies Residential Mortgage-backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	21,510
Securities held to maturity, fair value	21,606
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	341,041
Securities held to maturity, fair value	$ 344,840