Segment Disclosures (Details)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Disclosures [Abstract]
Number of reportable segments	1
Percentage of revenues from one customer (in hundredths)	11.50%	17.00%	19.00%

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration