Employee Benefits (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Tax Deferred Savings Plan [Abstract]
Employee Deferral Percent for 401(k)	100.00%
Company Matching Percent for 401(k)	5.00%
Company Discretionary Contribution for 401(k)	8.00%
Pension and Other Postretirement Benefit Contributions [Abstract]
Other Postretirement Benefits Payments	$ 1.4	$ 1.2	$ 1.1

The amount of cash or cash equivalents contributed during the reporting period by the entity to fund non-pension postretirement benefits.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3536-108585

Name:	us-gaap_OtherPostretirementBenefitsPayments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration