Commitments and Contingencies Commitments and Contingencies (Details) (Sales and Use Tax Refunds [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Sales and Use Tax Refunds [Member]
Gain Contingencies [Line Items]
Gain contingency, unrecorded amount	$ 15.6

The amount or range of possible amounts of gain that could be realized upon the resolution of a contingency.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 30

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6397426&loc=d3e17499-108355

Name:	us-gaap_GainContingencyUnrecordedAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant