Long-Term Debt (Narrative) (Details) (USD $)			3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Maximum [Member]	Mar. 31, 2012 Minimum [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Borrowing capacity of new revolving credit agreement	$ 450,000,000
Debt instruments interest rate base rate plus			1.75%	0.75%
Debt instruments interest rate Libor plus			2.75%	1.75%
Unused capacity commitment fee, percentage			0.50%	0.20%
Fixed rate senior secured notes	$ 75,000,000	$ 75,000,000
Senior secured notes, interest rate	6.04%