Segment Information - Revenues Classified by Major Geographic Areas (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 249,415	$ 231,838	$ 233,145	$ 238,214	$ 229,438	$ 231,619	$ 244,518	$ 253,417	$ 952,612	$ 958,992	$ 1,036,273
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									908,869	909,662	976,402
Europe / Middle East [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									28,431	28,858	28,077
Asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									7,613	11,301	16,511
South America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									$ 7,699	$ 9,171	$ 15,283