Investment Securities - Summary of Held-to-Maturity Securities, Unrealized Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Held-to-maturity Securities [Line Items]
Fair Value, Less than 12 months		$ 61,895
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(460)
Fair Value, 12 months or more	$ 181,317	167,754
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(2,229)	(4,014)
Total Fair Value	181,317	229,649
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	(2,229)	(4,474)
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]
Fair Value, Less than 12 months		26,660
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(381)
Fair Value, 12 months or more	141,907	126,475
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(938)	(2,324)
Total Fair Value	141,907	153,135
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	(938)	(2,705)
Other Residential MBS Issued or Guaranteed by U.S. Government Agencies or Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Fair Value, Less than 12 months		35,235
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(79)
Fair Value, 12 months or more	39,410	41,279
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,291)	(1,690)
Total Fair Value	39,410	76,514
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (1,291)	$ (1,769)