Real Estate Charges - Activity in the Liability Account Relating to Office Space Consolidation Initiatives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Real estate liability restructuring reserve [Abstract]
Balance as of January 1,	$ 148,429	$ 199,527
Expense (credit) incurred	2,258	(4,755)
Payments made	(38,920)	(50,893)
Interest accretion	4,297	4,550
Balance as of end of period	$ 116,064	$ 148,429