Business Combination - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Jun. 01, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Business Acquisition [Line Items]
Purchase price, cash				$ 471,400
Goodwill		$ 170,153		170,153		$ 6,788
Contingent consideration		51,690		51,690		$ 0
Other operating expenses		17,733	$ 11,392	51,195	$ 34,614
RidgeWorth
Business Acquisition [Line Items]
Purchase price	$ 547,100
Purchase price, cash	$ 471,400
Purchase price, shares issued (in shares)	213,669
Purchase price, shares issued, value	$ 21,700
Purchase price, price of shares issued (in dollars per share)	$ 101.76
Purchase price, contingent consideration	$ 51,700
Consideration transferred, deferred cash	2,300
Measurement period adjustment		1,000
Goodwill	163,365
Contingent consideration	51,700
Acquisition costs included in goodwill for tax purposes	6,400
Transaction and integration costs		4,900		22,900
Severance charges		1,500		10,100
Other operating expenses		1,200		8,500
Employment expenses		$ 2,200		4,300
RidgeWorth
Business Acquisition [Line Items]
Assets under management	40,100,000
Long term assets under management	35,700,000
Liquidity strategy assets under management	4,400,000
Consolidated entity excluding consolidated investment products | RidgeWorth
Business Acquisition [Line Items]
Purchase price	485,200
CLOs
Business Acquisition [Line Items]
Other operating expenses				$ 6,404
CLOs | RidgeWorth
Business Acquisition [Line Items]
Purchase price	$ 61,900