Schedule I - Condensed Financial Information of Registrant - Condensed Statements of Income (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
Condensed Financial Statements, Captions [Line Items]
Selling, general and administrative expense									$ 89,988	$ 86,343	$ 89,720
Operating income (loss)									95,655	136,443	55,925
Interest expense									4,237	6,658	7,427
Losses on extinguishment of debt										136	52
Interest and other non-operating income, net									281		53
Income (loss) from continuing operations	11,622	6,710	26,130	14,324	28,002	6,324	28,698	20,960	58,786	83,984	29,715
Equity in earnings of affiliate									(681)	(543)	(1,003)
Net loss from discontinued operations	62	2	97	21	14	18	53	57	182	142	141
Net income	11,560	6,708	26,033	14,303	27,988	6,306	28,645	20,903	58,604	83,842	29,574
Parent company [Member]
Condensed Financial Statements, Captions [Line Items]
Fees under service, tax, sharing and management agreements with subsidiaries									6,656	5,406	3,531
Selling, general and administrative expense									5,693	5,661	5,388
Other expense (income), net									(207)	453	(25)
Operating income (loss)									1,170	(708)	(1,832)
Interest expense									1,812	1,730	3,062
Losses on extinguishment of debt											52
Interest and other non-operating income, net									(2,442)	(1,264)	(973)
Income (loss) from continuing operations									1,800	(1,174)	(3,973)
Equity in earnings of affiliate									(56,986)	(85,158)	(33,688)
Net loss from discontinued operations									182	142	141
Net income									$ 58,604	$ 83,842	$ 29,574