Commitments and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Commitments and Contingencies.
Rent expense	$ 17,600,000	$ 13,200,000	$ 12,900,000
Duplicate rent charges	2,600,000	1,400,000
Charge recorded for remaining rent expense at the entity's old headquarters upon completion of the move	2,300,000
Minimum future rental commitments under non-cancelable operating leases
2014	16,265,000
2015	16,288,000
2016	15,144,000
2017	9,367,000
2018	8,841,000
2019 and thereafter	74,228,000
Total	140,133,000
Other Commitments
Maximum separation payments payable for early termination of employment arrangements without cause	4,800,000
Obligation to purchase market data, maintenance and other services	$ 55,500,000