Significant Customers (Details)	12 Months Ended
Dec. 31, 2012 customer	Dec. 31, 2011 customer	Dec. 31, 2010 customer
Significant Customers [Abstract]
Number of major customers	2	2	3
Percentage of revenue attriibuted to major customers	97.00%	99.00%	93.00%

Percentage of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues.

No definition available.

Name:	us-gaap_EntityWideRevenueMajorCustomerPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration