Segment Information - Wealth Management Segment Information (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting [Abstract]
Assets under management, administration, supervision and brokerage	$ 13,429.5	$ 12,968.7

The carrying amount of assets an investment adviser manages on behalf of investors.

No definition available.

Name:	us-gaap_AssetsUnderManagementCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant