Investments Available for Sale Securities in Unrealized Loss Position (Details) $ in Thousands		Dec. 31, 2016 USD ($) securities	Dec. 31, 2015 USD ($) securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 818,909	$ 505,312
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(22,042)	(4,896)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		44,907	66,938
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		(1,622)	(2,333)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		863,816	572,250
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ (23,664)	$ (7,229)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities		230	113
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 87,483	$ 40,606
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		476	262
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value		87,483	40,606
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 476	$ 262
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities		15	5
US Government and Government Agencies and Authorities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 19,094	$ 4,935
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(838)	(18)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		643	1,001
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		(16)	(9)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		19,737	5,936
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ (854)	$ (27)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities		4	3
US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 125,412	$ 167,691
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(2,259)	(1,345)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		125,412	167,691
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ (2,259)	$ (1,345)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities		18	24
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 182,395	$ 14,483
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(4,957)	(43)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		2,720	3,173
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		(33)	(73)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		185,115	17,656
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ (4,990)	$ (116)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities		109	12
Mortgage Backed Securities, Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	[1]	$ 492,008	$ 318,156
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	[1]	(13,988)	(3,486)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	[1]	41,544	62,753
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	[1]	(1,573)	(2,248)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	[1]	533,552	380,909
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	$ (15,561)	$ (5,734)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities	[1]	99	68
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	[1]	$ 87,483	$ 40,606
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	[1]	476	262
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	[1]	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	[1]	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	[1]	87,483	40,606
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	[1]	$ 476	$ 262
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities	[1]	15	5
Other Aggregated Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 0	$ 47
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		0	(4)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0	11
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0	(3)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		0	58
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 0	$ (7)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | securities		0	6

[1] All mortgage-backed securities are guaranteed by U.S. government agencies or Government-sponsored entities.