Securities (Details 2) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Available-for-sale securities
Less Than 12 Months, Fair Value	$ 181,673	$ 606,155
Less Than 12 Months, Unrealized Losses	504	6,211
12 Months or Longer, Fair Value	248,465	218,918
12 Months or Longer, Unrealized Losses	3,490	7,906
Total Fair Value	430,138	825,073
Total Unrealized Losses	3,994	14,117
Held-to-maturity debt securities
Less Than 12 Months, Fair Value	802	31,637
Less Than 12 Months, Unrealized Losses	3	448
12 Months or Longer, Fair Value	0	0
12 Months or Longer, Unrealized Losses	0	0
Total Fair Value	802	31,637
Total Unrealized Losses	3	448
Obligations of U.S. Sponsored Entities [Member]
Held-to-maturity debt securities
Less Than 12 Months, Fair Value		1,966
Less Than 12 Months, Unrealized Losses		4
12 Months or Longer, Fair Value		0
12 Months or Longer, Unrealized Losses		0
Total Fair Value		1,966
Total Unrealized Losses		4
Obligations of U.S. Government Sponsored Entities [Member]
Available-for-sale securities
Less Than 12 Months, Fair Value	700	183,697
Less Than 12 Months, Unrealized Losses	1	1,618
12 Months or Longer, Fair Value	698	5,844
12 Months or Longer, Unrealized Losses	1	177
Total Fair Value	1,398	189,541
Total Unrealized Losses	2	1,795
Held-to-maturity debt securities
Less Than 12 Months, Fair Value	802	29,671
Less Than 12 Months, Unrealized Losses	3	444
12 Months or Longer, Fair Value	0	0
12 Months or Longer, Unrealized Losses	0	0
Total Fair Value	802	29,671
Total Unrealized Losses	3	444
Obligations of U.S. States and Political Subdivisions [Member]
Available-for-sale securities
Less Than 12 Months, Fair Value	9,280	25,402
Less Than 12 Months, Unrealized Losses	35	141
12 Months or Longer, Fair Value	6,382	3,408
12 Months or Longer, Unrealized Losses	23	12
Total Fair Value	15,662	28,810
Total Unrealized Losses	58	153
Residential Mortgage-Backed Securities U.S. Government Agencies [Member]
Available-for-sale securities
Less Than 12 Months, Fair Value	31,122	32,636
Less Than 12 Months, Unrealized Losses	77	350
12 Months or Longer, Fair Value	26,216	30,244
12 Months or Longer, Unrealized Losses	441	966
Total Fair Value	57,338	62,880
Total Unrealized Losses	518	1,316
Residential Mortgage-Backed Securities U.S. Government Sponsored Entities [Member]
Available-for-sale securities
Less Than 12 Months, Fair Value	140,571	364,420
Less Than 12 Months, Unrealized Losses	391	4,102
12 Months or Longer, Fair Value	212,062	176,325
12 Months or Longer, Unrealized Losses	2,631	6,347
Total Fair Value	352,633	540,745
Total Unrealized Losses	3,022	10,449
U.S. corporate Debt Securities [Member]
Available-for-sale securities
Less Than 12 Months, Fair Value	0	0
Less Than 12 Months, Unrealized Losses	0	0
12 Months or Longer, Fair Value	2,163	2,163
12 Months or Longer, Unrealized Losses	338	338
Total Fair Value	2,163	2,163
Total Unrealized Losses	338	338
Equity Securities [Member]
Available-for-sale securities
Less Than 12 Months, Fair Value	0	0
Less Than 12 Months, Unrealized Losses	0	0
12 Months or Longer, Fair Value	944	934
12 Months or Longer, Unrealized Losses	56	66
Total Fair Value	944	934
Total Unrealized Losses	$ 56	$ 66