Debt (Narrative) (Details) (USD $)	3 Months Ended				3 Months Ended
	Mar. 31, 2014	Apr. 10, 2014 Subsequent Event [Member]	Mar. 31, 2014 Senior Secured Revolving Credit Facility [Member]	Dec. 31, 2013 Senior Secured Revolving Credit Facility [Member]	Mar. 31, 2014 Minimum [Member]	Mar. 31, 2014 Maximum [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,000,000,000
Line of credit facility, current borrowing capacity	470,000,000	570,000,000
Ratio of total debt to EBITDA	2.03					4.00
Current ratio	2.10				1.00
Line of credit facility amount outstanding			0	0
Letters of credit outstanding amount			$ 900,000