Business Segments - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) branch segment
Business segments
Number of reportable segments | segment	5
Regional Bank
Business segments
Number of full-service branches | branch	352
Regional Bank | Commercial Banking
Business segments
Segment reporting, annual revenue for customer benchmark (up to)	$ 500
U.S. Wholesale Banking
Business segments
Corporate customers revenues	$ 500