Commitments and Contingencies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended					12 Months Ended				12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Feb. 28, 2010	Dec. 31, 2012 Commitments	Dec. 31, 2012 Trilantic	Feb. 11, 2010 Trilantic	Dec. 31, 2012 EGL	Dec. 31, 2012 Pan	Dec. 31, 2012 Office Equipment	Dec. 31, 2011 Office Equipment	Dec. 31, 2010 Office Equipment	Dec. 31, 2012 Letter of Credit
Commitment And Contingencies [Line Items]
Rental expense relating to operating leases	$ 22,714	$ 16,136	$ 12,977							$ 627	$ 510	$ 593
Operating Leases agreements, expiration date	Various dates through 2023
Other Assets	14,067	11,718											3,500
Unfunded commitments for capital contributions	7,071
Line of credit intra-day facility	7,699
Basis points	0.10%
Contractual obligations related to the Tax Receivable Agreements					172,624
Payment to the counterparties to the Tax Receivable Agreement, within one year or less					7,274
Payment to the counterparties to the Tax Receivable Agreement, one to three years					26,582
Payment to the counterparties to the Tax Receivable Agreement, three to five years					29,874
Payment to the counterparties to the Tax Receivable Agreement, after five years					108,894
Issue of restricted share equivalents				500			500
Minimum Redemption value						16,500
Redemption date						Dec. 31, 2014
Minimum commitment in equity fund						5,000
Minimum Commitment in member's equity fund								50,000
Remaining Commitment to be paid									$ 5,654