Equity-Based Compensation - Schedule of Employee Stock Performance Activity (2.75x Performance Restricted Shares) (Detail) (Units Surrendered For Shares Plan [Member])	6 Months Ended
	Jun. 30, 2013
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PVUs surrendered for unvested Performance Restricted shares of stock (in shares)	4,165,861
2.75x Performance Restricted Shares [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, Beginning balance
Forfeited
Vested
Outstanding shares, ending balance	1,308,752
2.75x PVU Employee Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding units, beginning balance	225,051
Forfeited units	(2,964)
Vested
Outstanding units, ending balance
Two Point Seven Five Performance Vesting Units Surrendered For Two Point Seven Five Performance Restricted Shares [Member] | 2.75x Performance Restricted Shares [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PVUs surrendered for unvested Performance Restricted shares of stock (in shares)	1,308,752
Two Point Seven Five Performance Vesting Units Surrendered For Two Point Seven Five Performance Restricted Shares [Member] | 2.75x PVU Employee Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PVUs surrendered for unvested Performance Restricted shares of stock (in units)	(222,087)