Revenues by Geographic Area Based on Destination (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 654.7	$ 636.0	$ 608.9	$ 600.2	$ 541.8	$ 495.0	$ 483.9	$ 463.5	$ 2,499.8	$ 1,984.2	$ 1,937.7
% of Revenues									100.00%	100.00%	100.00%
UNITED STATES
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									1,296.4	1,005.6	943.3
% of Revenues									51.90%	50.70%	48.70%
Europe
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									606.0	495.1	449.3
% of Revenues									24.20%	25.00%	23.20%
Asia, Pacific Rim, Middle East and Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									$ 597.4	$ 483.5	$ 545.1
% of Revenues									23.90%	24.30%	28.10%