Summary of Significant Accounting Policies Summary of Significant Accounting Policies - Development Costs (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Planning Costs [Member]
Development Costs [Line Items]
Project development costs incurred	$ 10,800
Agreement Payments [Member]
Development Costs [Line Items]
Project development costs incurred	$ 750