Operations and Significant Accounting Policies - Concentraion of Credit Risk (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Customer Information [Line Items]
Major Customer, Percent of Total Revenue	12.30%	12.80%	12.50%
NewPage Bankruptcy Pre-Petition Receivable	$ 3.2
Large Power Customer [Member]
Customer Information [Line Items]
Number of Customers	9
Large Power Customers, Accounts Receivable	$ 11.6	9.3