Consolidated Company-Sponsored Investment Funds (Offsetting of Derivative Assets and Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivative Asset [Abstract]
Cash Collateral Received	$ (300)	$ (4,800)
VIEs
Derivative Asset [Abstract]
Gross Amounts of Recognized Assets	4,684	3,410
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	4,684	3,410
Financial Instruments	0	0
Cash Collateral Received	(1,351)	(856)
Net Amount	3,333	2,554
Derivative Liability [Abstract]
Gross Amounts of Recognized Liabilities	4,820	3,891
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	4,820	3,891
Financial Instruments	0	0
Cash Collateral Pledged	(3,368)	(829)
Net Amount	1,452	3,062
VOEs
Derivative Asset [Abstract]
Gross Amounts of Recognized Assets	8,127	3,816
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	8,127	3,816
Financial Instruments	0	0
Cash Collateral Received	(597)	(225)
Net Amount	7,530	3,591
Derivative Liability [Abstract]
Gross Amounts of Recognized Liabilities	5,504	3,830
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	5,504	3,830
Financial Instruments	0	0
Cash Collateral Pledged	(1,291)	(547)
Net Amount	$ 4,213	$ 3,283