Summary of Significant Accounting Policies (Details 2)			12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Minimum	Dec. 31, 2012 Maximum
Intangible assets - defined lives
Estimated useful lives			2 years	20 years
Insurance Losses
Discount rate for estimates of workers' compensation claims reserves (as a percent)	3.00%	3.00%

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration