Consolidated Company-Sponsored Investment Funds (Offsetting of Derivative Assets and Liabilities) (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Derivative Asset [Abstract]
Cash Collateral Received	$ 0	$ (800,000)
VIEs
Derivative Asset [Abstract]
Gross Amounts of Recognized Assets	16,767,000	4,997,000
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	16,767,000	4,997,000
Financial Instruments	0	0
Cash Collateral Received	(186,000)	(461,000)
Net Amount	16,581,000	4,536,000
Derivative Liability [Abstract]
Gross Amounts of Recognized Liabilities	2,668,000	2,081,000
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	2,668,000	2,081,000
Financial Instruments	0	0
Cash Collateral Pledged	(2,668,000)	(2,081,000)
Net Amount	0	$ 0
VOEs
Derivative Asset [Abstract]
Gross Amounts of Recognized Assets	80,000
Gross Amounts Offset in the Statement of Financial Position	0
Net Amounts of Assets Presented in the Statement of Financial Position	80,000
Financial Instruments	0
Cash Collateral Received	(12,000)
Net Amount	68,000
Derivative Liability [Abstract]
Gross Amounts of Recognized Liabilities	135,000
Gross Amounts Offset in the Statement of Financial Position	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	135,000
Financial Instruments	0
Cash Collateral Pledged	(34,000)
Net Amount	$ 101,000