Consolidation Consolidated Federated Fund VIEs (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Investments—consolidated investment companies	$ 45,411	$ 58,072
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	12,700	14,900
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	900	2,300
Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Variable Interest Entity [Line Items]
Investments—consolidated investment companies	39,700	43,200
Less: Liabilities	400	700
Less: Redeemable noncontrolling interest in subsidiaries	27,700	28,300
Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member] | Cash and Cash Equivalents [Member]
Variable Interest Entity [Line Items]
Consolidated VIE assets	100	0
Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member] | Trade Accounts Receivable [Member]
Variable Interest Entity [Line Items]
Consolidated VIE assets	$ 1,000	$ 700