Investment Securities - Summary of Held-to-maturity Investment Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	$ 221,727	$ 235,398
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	109	2
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(2,229)	(4,474)
Fair value	219,607	230,926
Residential Mortgage Pass-Through Securities Issued or Guaranteed by U.S. Government Agencies or Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	147,221	157,115
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	33	2
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(938)	(2,705)
Fair value	146,316	154,412
Other Residential MBS Issued or Guaranteed by U.S. Government Agencies or Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	74,506	78,283
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	76
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(1,291)	(1,769)
Fair value	$ 73,291	$ 76,514