Consolidated Sponsored Investment Products - Reconciliation of Assets Related to Consolidated Sponsored Investment Products (Detail) (Debt Securities [Member], USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014
Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 0
Purchases	450
Ending balance	$ 450