Summary of Significant Accounting Policies Allowance for Doubtful Accounts (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Allowance for Doubtful Accounts Receivable [Roll Forward]      
Allowance for Doubtful Accounts Receivable $ 170 $ 0 $ 0
Provision for Doubtful Accounts 0 170 0
Allowance for Doubtful Accounts Receivable, Charge-offs (170) 0 0
Allowance for Doubtful Accounts Receivable $ 0 $ 170 $ 0