Goodwill and Other Intangible Assets - (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($)
Goodwill [Roll Forward]
Balance at January 1, 2016	$ 445,871
Addition to goodwill from KeyWorth acquisition	20,634
Adjustment to previously recorded goodwill	4,029
Balance at June 30, 2016	470,534
Community Banks
Goodwill [Roll Forward]
Balance at January 1, 2016	443,104
Addition to goodwill from KeyWorth acquisition	20,634
Adjustment to previously recorded goodwill	4,029
Balance at June 30, 2016	467,767
Insurance
Goodwill [Roll Forward]
Balance at January 1, 2016	2,767
Addition to goodwill from KeyWorth acquisition	0
Adjustment to previously recorded goodwill	0
Balance at June 30, 2016	$ 2,767