Lease Exit and Related Charges (Changes to Accrued Loss on Excess Office Facilities) (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013 term	Jun. 30, 2013	Sep. 30, 2013 stage
Disclosure Changes To Accrued Loss On Excess Office Facilities [Abstract]
Leases term	11 years
Number of extensions	2
Extension term	5 years
Early termination, number of stages			3
Loss on contract termination			$ 6,600,000
Cash paid for contract termination fees	3,100,000	3,200,000	6,300,000
Accrued loss December 31, 2011			4,213,000
Additions and adjustments to the lease exit charges accrual, including sublease income estimate revision			1,331,000
Less amounts paid, net of sublease income			4,953,000
Accrued loss June 30, 2013 (included in Accrued and other current liabilities)	$ 591,000		$ 591,000