Securities - AFS in an Unrealized Loss Position (Details) $ in Thousands	Mar. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($) item
Number of Securities
Unrealized loss for less than twelve months | item	14	41
Unrealized loss for twelve months or longer | item	22	49
Total | item	36	90
Fair Value
Unrealized loss for less than twelve months	$ 75,018	$ 217,328
Unrealized loss for twelve months or longer	86,048	116,001
Estimated Fair Value, Total	161,066	333,329
Unrealized Loss
Unrealized loss for less than twelve months	892	2,135
Unrealized loss for twelve months or longer	1,142	3,181
Total	$ 2,034	$ 5,316
U.S. Treasury securities
Number of Securities
Unrealized loss for less than twelve months | item	3	8
Unrealized loss for twelve months or longer | item	2
Total | item	5	8
Fair Value
Unrealized loss for less than twelve months	$ 4,304	$ 33,791
Unrealized loss for twelve months or longer	2,457
Estimated Fair Value, Total	6,761	33,791
Unrealized Loss
Unrealized loss for less than twelve months	5	33
Unrealized loss for twelve months or longer	3
Total	$ 8	$ 33
Bonds
Number of Securities
Unrealized loss for less than twelve months | item	1	7
Unrealized loss for twelve months or longer | item	1	3
Total | item	2	10
Fair Value
Unrealized loss for less than twelve months	$ 54,820	$ 148,327
Unrealized loss for twelve months or longer	34,865	44,321
Estimated Fair Value, Total	89,685	192,648
Unrealized Loss
Unrealized loss for less than twelve months	152	896
Unrealized loss for twelve months or longer	128	1,051
Total	$ 280	$ 1,947
Residential mortgage-backed securities
Number of Securities
Unrealized loss for less than twelve months | item	1	3
Unrealized loss for twelve months or longer | item	1	1
Total | item	2	4
Fair Value
Unrealized loss for less than twelve months	$ 1,311	$ 3,407
Unrealized loss for twelve months or longer	976	982
Estimated Fair Value, Total	2,287	4,389
Unrealized Loss
Unrealized loss for less than twelve months	1	5
Unrealized loss for twelve months or longer	13	14
Total	$ 14	$ 19
Commercial mortgage-backed securities
Number of Securities
Unrealized loss for less than twelve months | item	1	1
Total | item	1	1
Fair Value
Unrealized loss for less than twelve months	$ 1,605	$ 1,611
Estimated Fair Value, Total	1,605	1,611
Unrealized Loss
Unrealized loss for less than twelve months	2	2
Total	$ 2	$ 2
Collateralized mortgage obligations
Number of Securities
Unrealized loss for less than twelve months | item	2	2
Unrealized loss for twelve months or longer | item	8	8
Total | item	10	10
Fair Value
Unrealized loss for less than twelve months	$ 933	$ 1,590
Unrealized loss for twelve months or longer	40,304	42,399
Estimated Fair Value, Total	41,237	43,989
Unrealized Loss
Unrealized loss for less than twelve months	4	4
Unrealized loss for twelve months or longer	637	1,640
Total	$ 641	$ 1,644
Corporate securities
Number of Securities
Unrealized loss for less than twelve months | item	2	16
Unrealized loss for twelve months or longer | item		1
Total | item	2	17
Fair Value
Unrealized loss for less than twelve months	$ 2,820	$ 16,635
Unrealized loss for twelve months or longer		1,949
Estimated Fair Value, Total	2,820	18,584
Unrealized Loss
Unrealized loss for less than twelve months	17	277
Unrealized loss for twelve months or longer		49
Total	$ 17	$ 326
States and political subdivisions
Number of Securities
Unrealized loss for less than twelve months | item	3	2
Unrealized loss for twelve months or longer | item	8	35
Total | item	11	37
Fair Value
Unrealized loss for less than twelve months	$ 702	$ 3,018
Unrealized loss for twelve months or longer	5,125	24,423
Estimated Fair Value, Total	5,827	27,441
Unrealized Loss
Unrealized loss for less than twelve months	2	9
Unrealized loss for twelve months or longer	12	93
Total	$ 14	$ 102
Equity securities
Number of Securities
Unrealized loss for less than twelve months | item	1	2
Unrealized loss for twelve months or longer | item	2	1
Total | item	3	3
Fair Value
Unrealized loss for less than twelve months	$ 8,523	$ 8,949
Unrealized loss for twelve months or longer	2,321	1,927
Estimated Fair Value, Total	10,844	10,876
Unrealized Loss
Unrealized loss for less than twelve months	709	909
Unrealized loss for twelve months or longer	349	334
Total	$ 1,058	$ 1,243