Pension Benefits And Other Postretirement Benefits Recognized In the Accompanying Consolidated Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Other noncurrent assets	$ 355	$ 0
Deferred tax asset	10,972	9,834
Total assets	11,327	9,834
Current liabilities	(4,411)	(3,462)
Long-term liabilities	(157,843)	(108,496)
Deferred tax liability	(269)	(22)
Total liabilities	(162,523)	(111,980)
Accumulated other comprehensive income	32,002	29,050
Net amount recognized	(119,194)	(73,096)
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Other noncurrent assets	0	0
Deferred tax asset	1,247	1,113
Total assets	1,247	1,113
Current liabilities	(978)	(1,099)
Long-term liabilities	(11,240)	(10,508)
Deferred tax liability	0	0
Total liabilities	(12,218)	(11,607)
Accumulated other comprehensive income	1,984	1,772
Net amount recognized	$ (8,987)	$ (8,722)