Debt 2 (Details) (USD $)	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Revolving Credit Facility due June 2018 [Member]	Mar. 31, 2013 Revolving Credit Facility due August 2016 [Member]	Jun. 30, 2013 Base Rate Borrowings [Member]	Jun. 30, 2013 Eurocurrency Rate Borrowings [Member]
Debt (Textual) [Abstract]
Maximum committed amount available under revolving credit facility			$ 1,000,000,000
Maximum available credit increase under revolving credit facility			500,000,000
Borrowings outstanding under revolving credit facility			0	0
Interest rate that would have applled at June 30, 2013 to a borrowing under revolving credit facility due June 2018					3.38%	1.19%
Debt issuance costs	$ 1,000,000	$ 0	$ 1,000,000
Covenant description			The revolving credit facility due June 2018 contains customary covenants for borrowings of this type, including two financial covenants: (i) for the 12 months ending each quarter-end, the ratio of consolidated debt for borrowed money to consolidated cash flow, each as defined in the Credit Agreement, must not exceed 4.00 to 1.00; and (ii) for the 12 months ending at any date, the ratio of consolidated cash flow to the sum of interest payable on, and amortization of debt discount in respect of, all consolidated debt for borrowed money, as defined in the Credit Agreement, must not be less than 3.50 to 1.00.
Financial covenant ratio of consolidated debt to consolidated cash flow			400.00%
Financial covenant ratio of consolidated cash flow to sum of interest payable and amortization of debt discount			350.00%
Covenant compliance			At June 30, 2013, the Company was in compliance with all covenants.