Commitments and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Commitments and Contingencies.
Rent expense	$ 13,200,000	$ 12,900,000	$ 14,000,000
Minimum future rental commitments under non-cancelable operating leases
2013	15,139,000
2014	14,036,000
2015	13,046,000
2016	12,228,000
2017	8,628,000
2018 and thereafter	74,646,000
Total	137,723,000
Other Commitments
Maximum separation payments payable for early termination of employment arrangements without cause	5,800,000
Obligation to purchase market data, maintenance and other services	$ 53,000,000