Condensed Consolidating Financial Information (Narrative) (Details) (USD $)	Dec. 31, 2012	Feb. 28, 2012 Eight Point Six Two Five Percent Senior Notes [Member]	Nov. 17, 2011 Eight Point Six Two Five Percent Senior Notes [Member]	Jun. 30, 2011 Eight Point Six Two Five Percent Senior Notes [Member]	Nov. 02, 2010 Eight Point Six Two Five Percent Senior Notes [Member]	Sep. 10, 2012 Seven Point Five Percent Senior Notes [Member]
Condensed Consolidating Financial Information [Line Items]
Aggregate principal amount		$ 200,000,000	$ 200,000,000	$ 400,000,000	$ 400,000,000	$ 300,000,000
Debt instrument interest rate					8.625%	7.50%
Voting interest of the subsidiary owned by the registrant	100.00%