Acquisitions and Divestitures (Merger and Integration Expenses) (Details) - Capital Bank Financial Corp - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Business Acquisition [Line Items]
Merger and integration expense	$ 41,802	$ 71,862
Professional fees
Business Acquisition [Line Items]
Merger and integration expense	8,989	14,621
Employee compensation, incentives and benefits
Business Acquisition [Line Items]
Merger and integration expense	2,548	6,494
Contract employment and outsourcing
Business Acquisition [Line Items]
Merger and integration expense	1,704	3,103
Occupancy
Business Acquisition [Line Items]
Merger and integration expense	2,214	2,221
Miscellaneous expense
Business Acquisition [Line Items]
Merger and integration expense	3,103	5,138
All other expense
Business Acquisition [Line Items]
Merger and integration expense	$ 23,244	$ 40,285