Commitments and Contingencies (Detail) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commitments and Contingencies.
Rent expense		$ 12,400,000	$ 17,600,000	$ 13,200,000
Duplicate rent charges	2,600,000		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		17,214,000
2015		15,361,000
2016		9,418,000
2017		8,835,000
2019 and thereafter		74,228,000
Total		125,056,000
Other Commitments
Maximum separation payments payable for early termination of employment arrangements without cause		5,400,000
Obligation to purchase market data, maintenance and other services		$ 42,300,000