Securities (Details) - Securities In An Unrealized Loss Position $ in Thousands	Dec. 31, 2016 USD ($) security	Dec. 31, 2015 USD ($) security
Securities in An Unrealized Loss Position [Line Items]
Number of Securities | security	695	252
Fair Value - Less Than 12 Months	$ 974,337	$ 428,035
Unrealized Losses - Less Than 12 Months	18,720	4,897
Fair Value - 12 Months or Longer	567,538	337,516
Unrealized Losses - 12 Months or Longer	23,976	22,534
Fair Value - Total	1,541,875	765,551
Unrealized Losses - Total	$ 42,696	$ 27,431
U.S. treasury securities
Securities in An Unrealized Loss Position [Line Items]
Number of Securities | security	16	4
Fair Value - Less Than 12 Months	$ 33,505	$ 7,946
Unrealized Losses - Less Than 12 Months	61	35
Fair Value - 12 Months or Longer	3,995	0
Unrealized Losses - 12 Months or Longer	5	0
Fair Value - Total	37,500	7,946
Unrealized Losses - Total	$ 66	$ 35
U.S. agency securities
Securities in An Unrealized Loss Position [Line Items]
Number of Securities | security	28	10
Fair Value - Less Than 12 Months	$ 62,064	$ 30,620
Unrealized Losses - Less Than 12 Months	364	169
Fair Value - 12 Months or Longer	11,814	0
Unrealized Losses - 12 Months or Longer	46	0
Fair Value - Total	73,878	30,620
Unrealized Losses - Total	$ 410	$ 169
CMOs
Securities in An Unrealized Loss Position [Line Items]
Number of Securities | security	194	133
Fair Value - Less Than 12 Months	$ 523,233	$ 309,787
Unrealized Losses - Less Than 12 Months	10,309	3,110
Fair Value - 12 Months or Longer	411,758	257,362
Unrealized Losses - 12 Months or Longer	7,344	5,975
Fair Value - Total	934,991	567,149
Unrealized Losses - Total	$ 17,653	$ 9,085
MBSs
Securities in An Unrealized Loss Position [Line Items]
Number of Securities | security	68	27
Fair Value - Less Than 12 Months	$ 221,174	$ 63,028
Unrealized Losses - Less Than 12 Months	4,726	427
Fair Value - 12 Months or Longer	77,780	31,980
Unrealized Losses - 12 Months or Longer	1,154	444
Fair Value - Total	298,954	95,008
Unrealized Losses - Total	$ 5,880	$ 871
Municipal securities
Securities in An Unrealized Loss Position [Line Items]
Number of Securities | security	380	68
Fair Value - Less Than 12 Months	$ 133,957	$ 8,135
Unrealized Losses - Less Than 12 Months	3,059	65
Fair Value - 12 Months or Longer	29,280	24,227
Unrealized Losses - 12 Months or Longer	659	245
Fair Value - Total	163,237	32,362
Unrealized Losses - Total	$ 3,718	$ 310
CDOs
Securities in An Unrealized Loss Position [Line Items]
Number of Securities | security	7	8
Fair Value - Less Than 12 Months	$ 0	$ 8,034
Unrealized Losses - Less Than 12 Months	0	971
Fair Value - 12 Months or Longer	30,592	21,642
Unrealized Losses - 12 Months or Longer	14,682	15,821
Fair Value - Total	30,592	29,676
Unrealized Losses - Total	$ 14,682	$ 16,792
Equity securities
Securities in An Unrealized Loss Position [Line Items]
Number of Securities | security	2	2
Fair Value - Less Than 12 Months	$ 404	$ 485
Unrealized Losses - Less Than 12 Months	201	120
Fair Value - 12 Months or Longer	2,319	2,305
Unrealized Losses - 12 Months or Longer	86	49
Fair Value - Total	2,723	2,790
Unrealized Losses - Total	$ 287	$ 169
Municipal securities
Schedule of Held-to-Maturity Securities [Line Items]
Number of Securities | security	14	19
Fair Value - Less than 12 Months	$ 0	$ 20,054
Unrealized Losses - Less than 12 Months	0	3,098
Fair Value - 12 Months or Longer	18,212	0
Unrealized Losses - 12 Months or Longer	4,079	0
Fair Value - Total	18,212	20,054
Unrealized Losses - Total	$ 4,079	$ 3,098