Segment Information - Revenue Classified by Major Geographic Areas (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 293,362	$ 243,376	$ 243,830	$ 239,146	$ 249,415	$ 231,838	$ 233,145	$ 238,214	$ 1,019,714	$ 952,612	$ 958,992
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									974,260	908,870	909,661
Europe/Middle East [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									36,516	34,913	36,363
Asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									4,949	1,131	3,797
South America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									$ 3,989	$ 7,698	$ 9,171