Segment Information - General Corporate Expenses and Other Business Operations, Net (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
Segment Reporting Information [Line Items]
Gross profit-Other	$ 40,370	$ 33,187	$ 65,735	$ 44,444	$ 62,821	$ 34,257	$ 72,086	$ 53,854	$ 183,736	$ 223,018	$ 138,625
Selling, general and administrative:
Total selling, general and administrative									89,988	86,343	89,720
Other income									3,811	3,938	8,427
Other expense									2,118	3,823	1,262
Operating income									95,655	136,443	55,925
Other [Member]
Segment Reporting Information [Line Items]
Gross profit-Other									5,063	4,153	2,966
Selling, general and administrative:
Personnel costs									(9,994)	(8,418)	(7,865)
Professional fees									(4,117)	(3,805)	(3,784)
All other									(3,568)	(4,224)	(3,040)
Total selling, general and administrative									(17,679)	(16,447)	(14,689)
Other income									394	118	366
Other expense									(58)	(643)	(4)
Operating income									$ (12,280)	$ (12,819)	$ (11,361)