Fair Value - Fair Value of Contingently Convertible Series E Units Liability (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013
Fair Value Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Contingently convertible Series E units liability	$ 65,319	$ 65,319
Remeasurement of Series E units included in earnings	(438)	(438)
Contingently convertible Series E units liability, Ending Balance	65,319	65,319
Contingently Convertible Series E Units Liability [Member]
Fair Value Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Contingently convertible Series E units liability	65,319	65,319
Contingently convertible Series E units liability, Beginning Balance	64,881
Remeasurement of Series E units included in earnings	438
Contingently convertible Series E units liability, Ending Balance	65,319	65,319
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Contingently convertible Series E units liability
Contingently convertible Series E units liability, Ending Balance
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Contingently convertible Series E units liability
Contingently convertible Series E units liability, Ending Balance
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Contingently convertible Series E units liability	65,319	65,319
Contingently convertible Series E units liability, Ending Balance	$ 65,319	$ 65,319