Commitments and Contingencies - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended							6 Months Ended	12 Months Ended
	Jun. 13, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Dec. 21, 2012	Jun. 30, 2013 Affinion Group, LLC [Member]	Jun. 30, 2013 Asia Private Credit ("APC") [Member]	Dec. 31, 2012 Asia Private Credit ("APC") [Member]	Jun. 30, 2013 CPI Capital Partners North America LP [Member]	Dec. 31, 2012 CPI Capital Partners North America LP [Member]	Mar. 28, 2013 CPI Capital Partners North America LP [Member]	Apr. 30, 2012 Stone Tower [Member]	Jun. 30, 2013 Gulf Stream acquisition [Member]	Dec. 31, 2012 Gulf Stream acquisition [Member]
Long-term Purchase Commitment [Line Items]
Maximum exposure relating to the financial guarantees		$ 3,200,000		$ 3,200,000
Unfunded capital commitments		446,300,000		446,300,000		258,300,000
Aggregate after-tax cash distribution obligation to acquire additional common units		25.00%		25.00%
Capital support to athene							100,000,000
Ownership stake								69.00%
Number of days to respond complaints on defendants deadlines	21 days
Expenses related to non-cancellable contractual obligations		10,700,000	10,100,000	21,300,000	19,500,000
Cumulative revenues recognized if existing investments become worthless		4,000,000,000		4,000,000,000
General partner obligation return previously distributed carried interest income									300,000	300,000
Fair value of contingent consideration liability		107,342,000		107,342,000										117,700,000
Fair value of the contingent obligation		94,200,000		94,200,000		126,900,000
Fair Value of Contingent Consideration liability												1,200,000			13,100,000	14,100,000
Discounted cash flows												7.00%
Contingent liability paid in cash													500,000
Net realized after tax profit to contingent liability													25.00%
Remaining liability reversed to other income											$ 700,000