Summary of Significant Accounting Policies (Narrative)(Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of Significant Accounting Policies
Contingent acquisition liability adjustment	$ 1,065,000
Interest differentials paid	$ 500,000	$ 1,300,000	$ 4,800,000