Fair Value Measurements (Assets and Liabilities Measured at Fair Value on Recurring Basis) (Detail) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted assets	$ 41,704	$ 40,870
Contingent consideration	(72,448)	(70,165)
Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instrument - net	(11,531)	(7,094)
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted assets	41,704	40,870
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instrument - net	(11,531)	(7,094)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	(72,448)	(70,165)
Fuel [Member] | Commodity Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instrument - net	(1,881)	(1,979)
Fuel [Member] | Fair Value, Inputs, Level 3 [Member] | Commodity Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instrument - net	$ (1,881)	$ (1,979)