Debt and Lease Obligations (Senior Credit Facility) (Details) (USD $)	12 Months Ended			9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2013	Oct. 04, 2013	Oct. 03, 2013
Line of Credit Facility [Line Items]
Repayments of Long-term Debt	$ 40,000,000	$ 25,000,000	$ 480,000,000
Interest Rate Swap | Designated as Hedging Instrument
Line of Credit Facility [Line Items]
Derivative, notional amount	40,000,000	140,000,000
Letter of Credit
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	300,000,000
Term Loan Facility
Line of Credit Facility [Line Items]
Debt Instrument, Face Amount	400,000,000
Repayments of Long-term Debt	40,000,000	25,000,000	5,000,000
Credit Facilities Scheduled Repayments Due in Next three Quarters	10,000,000
Credit Facilities Scheduled Repayments Due in the fourth Quarter of next year	15,000,000
Senior Credit Facility
Line of Credit Facility [Line Items]
Debt Instrument, Maturity Date				Oct. 04, 2018
Letters of Credit Outstanding, Amount	76,800,000	106,100,000
Domestic subsidiaries unconditional guarantee	100.00%
Maximum permitted leverage ratio, Debt to Total Consolidated EBITDA	3.25
Minimum interest coverage, consolidated EBITDA to Total Interest Expense	3.25
Line of Credit Facility, Commitment Fee Percentage	0.175%
Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity					1,000,000,000	850,000,000
Line of Credit Facility, Amount Outstanding	0
Line of Credit Facility, Current Borrowing Capacity	923,200,000	893,900,000
Swingline loan
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	30,000,000
Term Loan Or Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit agreement maximum borrowing capacity increase in additional borrowings	400,000,000
Prior Credit Agreement
Line of Credit Facility [Line Items]
Repayments of Debt			$ 12,500,000