Selected Segment Financial Data, Assets (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Segment Reporting Information [Line Items]
Assets	$ 1,228,676		$ 664,642
Americas - United States
Segment Reporting Information [Line Items]
Assets	891,905	[1]	408,038	[1]
Americas - Other
Segment Reporting Information [Line Items]
Assets	26,753		26,664
EMEA
Segment Reporting Information [Line Items]
Assets	227,358		166,997
Asia /Pacific
Segment Reporting Information [Line Items]
Assets	$ 82,660		$ 62,943

[1] The goodwill related to the S1 acquisition is included in Americas - United States as of March 31, 2012. See Note 5 for further discussion.