Summary of Termination Benefit Obligations (Detail) (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period	$ 64	$ 529
Termination benefits accrued	1,451	867
Employee, office and other costs accrued	172	5,567
Cash payments	(420)	(6,963)
Balance at end of period	$ 1,267