Segment Information - Revenue Classified by Major Geographic Areas (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
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 249,689	$ 243,830	$ 504,857	$ 482,976
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	236,440	232,781	476,352	461,474
Europe/Middle East [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	10,040	9,317	23,877	17,720
Asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	2,765	709	3,768	1,534
South America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 444	$ 1,023	$ 860	$ 2,248