Revenues by Geographic Area Based on Destination (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues	$ 803.2	$ 766.7	$ 768.1	$ 747.3	$ 654.7	$ 636.0	$ 608.9	$ 600.2	$ 3,085.3	$ 2,499.8	$ 1,984.2
% of Revenues									100.00%	100.00%	100.00%
UNITED STATES
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues									1,499.5	1,296.4	1,005.6
% of Revenues									48.60%	51.90%	50.70%
Europe
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues									755.9	606.0	495.1
% of Revenues									24.50%	24.20%	25.00%
Asia, Pacific Rim, Middle East and other
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues									$ 829.9	$ 597.4	$ 483.5
% of Revenues									26.90%	23.90%	24.30%