Capital Lease Obligations - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012
Corporate office space - Atlanta, Georgia
Schedule of Capital Lease Obligations [Line Items]
Increase in leased property and equipment	$ 7.4
Capital Lease Obligations
Schedule of Capital Lease Obligations [Line Items]
Capital leases expiration dates	2013 to 2023

Current year acquisitions of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.

No definition available.

Name:	us-gaap_PropertyPlantAndEquipmentAdditions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration