Investment Securities - (Summary of Unrealized Losses) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	$ 15,714	$ 176,709
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(30)	(920)
12 months or more, Fair Value	461,067	575,954
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(3,680)	(19,012)
Total, Fair Value	476,781	752,663
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(3,710)	(19,932)
Residential Mortgage Pass-Through Securities Issued or Guaranteed by U.S. Government Agencies or Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value		109,182
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(516)
Total, Fair Value		109,182
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		(516)
Other Residential MBS Issued or Guaranteed by U.S. Government Agencies or Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	15,714	67,527
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(30)	(404)
12 months or more, Fair Value	461,067	575,954
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(3,680)	(19,012)
Total, Fair Value	476,781	643,481
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (3,710)	$ (19,416)