Benefit Plans Narrative (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Benefit Plans [Abstract]
Defined Contribution Plan, Administrative Expenses	$ 6.5	$ 6.1	$ 3.1

Amount of administrative expenses incurred by a defined contribution plan.

No definition available.

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