Goodwill and Identifiable Intangible Assets - Goodwill by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Goodwill, beginning of period	$ 379,627	$ 379,627
Adjustment	0	0
Balance, end of period	379,627	379,627
General Banking [Member]
Goodwill [Roll Forward]
Goodwill, beginning of period	334,603	334,603
Adjustment	0	0
Balance, end of period	334,603	334,603
Insurance [Member]
Goodwill [Roll Forward]
Goodwill, beginning of period	45,024	45,024
Adjustment	0	0
Balance, end of period	$ 45,024	$ 45,024