Subsequent Event (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Feb. 01, 2013 5.375% Senior Notes [Member] Subsequent Event [Member]	Dec. 31, 2012 5.375% Senior Notes [Member] Subsequent Event [Member]	Dec. 31, 2012 8.50% Senior Notes [Member]	Nov. 30, 2009 8.50% Senior Notes [Member]
Subsequent Event [Line Items]
Long-term debt outstanding	$ 200,000	$ 200,000	$ 500,000			$ 200,000
Senior notes interest rate			5.375%			8.50%
Debt instrument, redeemable notes purchase price, percentage				101.00%	101.00%
Redemption price prior to maturity percent				100.00%