Components of Current and Deferred Income Tax Expense (Benefit) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Current income tax expense:
Federal and foreign									$ 573	$ 11,965	$ 25,833
State and local									340	97	142
Subtotal									913	12,062	25,975
Deferred income tax expense (benefit):
Federal and foreign									6,224	17,189	(2,285)
State and local
Subtotal									6,224	17,189	(2,285)
Income tax expense (benefit)	$ 2,122	$ 4,476	$ 5,032	$ (4,493)	$ 7,592	$ 7,091	$ 8,223	$ 6,345	$ 7,137	$ 29,251	$ 23,690