Investment Securities - Investments' Gross Unrealized Losses and Fair Value Aggregated by Investment Category and Length of Time in Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair Value
Less than 12 Months	$ 9,506	$ 90,954
12 Months or Longer	5,042	2,101
Total	14,548	93,055
Gross Unrealized Losses
Less than 12 Months	103	505
12 Months or Longer	44	73
Total	147	578
Fair Value
Less than 12 Months	3,179	69,641
12 Months or Longer	5,457	14,888
Total	8,636	84,529
Gross Unrealized Losses
Less than 12 Months	48	519
12 Months or Longer	26	283
Total	74	802
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Less than 12 Months, Fair Value	12,685	160,595
12 Months or Longer, Fair Value	10,499	16,989
Total, Fair Value	23,184	177,584
Less than 12 Months, Gross Unrealized Losses	151	1,024
12 Months or Longer, Gross Unrealized Losses	70	356
Total, Gross Unrealized Losses	221	1,380
State and municipal
Fair Value
Less than 12 Months	8,375	$ 7,558
12 Months or Longer	1,197
Total	9,572	$ 7,558
Gross Unrealized Losses
Less than 12 Months	98	$ 60
12 Months or Longer	9
Total	107	$ 60
U.S. Government-sponsored mortgage-backed securities
Fair Value
Less than 12 Months	1,131	83,396
12 Months or Longer	3,845	2,101
Total	4,976	85,497
Gross Unrealized Losses
Less than 12 Months	5	445
12 Months or Longer	35	73
Total	40	$ 518
State and municipal
Fair Value
Less than 12 Months	3,179
12 Months or Longer	673	$ 1,982
Total	3,852	$ 1,982
Gross Unrealized Losses
Less than 12 Months	48
12 Months or Longer	1	$ 15
Total	$ 49	15
U.S. Government-sponsored mortgage-backed securities
Fair Value
Less than 12 Months		69,641
12 Months or Longer	$ 4,784	12,906
Total	$ 4,784	82,547
Gross Unrealized Losses
Less than 12 Months		519
12 Months or Longer	$ 25	268
Total	$ 25	$ 787