Depreciation and Amortization - Depreciation and Amortization Expense for Property and Equipment and Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Property, Plant and Equipment [Line Items]
Total depreciation and amortization expense	$ 4,964	$ 4,749	$ 9,812	$ 9,374
Operating expenses [Member]
Property, Plant and Equipment [Line Items]
Total depreciation and amortization expense	4,847	4,674	9,579	9,225
Corporate general and administrative expenses [Member]
Property, Plant and Equipment [Line Items]
Total depreciation and amortization expense	$ 117	$ 75	$ 233	$ 149