Consolidated Company-Sponsored Investment Funds (Offsetting of Derivative Assets and Liabilities) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Derivative Asset [Abstract]
Cash Collateral Received	$ (300)	$ (4,800)
VIEs
Derivative Asset [Abstract]
Gross Amounts of Recognized Assets	4,029	3,410
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	4,029	3,410
Financial Instruments	0	0
Cash Collateral Received	(1,351)	(856)
Net Amount	2,678	2,554
Derivative Liability [Abstract]
Gross Amounts of Recognized Liabilities	4,003	3,891
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	4,003	3,891
Financial Instruments	0	0
Cash Collateral Pledged	(2,690)	(829)
Net Amount	1,313	3,062
VOEs
Derivative Asset [Abstract]
Gross Amounts of Recognized Assets	1,117	3,816
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	1,117	3,816
Financial Instruments	0	0
Cash Collateral Received	(422)	(225)
Net Amount	695	3,591
Derivative Liability [Abstract]
Gross Amounts of Recognized Liabilities	1,267	3,830
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	1,267	3,830
Financial Instruments	0	0
Cash Collateral Pledged	(824)	(547)
Net Amount	$ 443	$ 3,283