Loss on Excess Office Facilities (Changes to Accrued Loss on Excess Office Facilities) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Disclosure Changes To Accrued Loss On Excess Office Facilities [Abstract]
Accrued loss December 31, 2011	$ 4,213
Less amounts paid, net of sublease income	642
Accrued loss September 30, 2012	3,571
Less current portion	(2,460)	(2,463)
Accrued loss, non-current portion	$ 1,111