Long-Term Debt (Senior Notes Narrative) (Details) (Senior Notes [Member], USD $)					0 Months Ended
	Jun. 30, 2013 6.5% Senior Notes [Member]	Jun. 21, 2013 6.5% Senior Notes [Member]	Sep. 30, 2012 6.5% Senior Notes [Member]	Jan. 18, 2012 6.5% Senior Notes [Member]	Jun. 30, 2013 Add- On to the 6.5% Senior Notes [Member]	Jun. 21, 2013 Add- On to the 6.5% Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount	$ 650,000,000	$ 650,000,000		$ 450,000,000		$ 200,000,000
Stated interest rate	6.50%	6.50%	6.50%
Proceeds from debt, net of issuance costs					211,600,000
Accrued interest						5,100,000
Debt premium						$ 8,500,000
Effective interest rate		6.26%				5.72%