Debt (Revolving Credit Agreement) (Narrative) (Details) - USD ($) $ in Millions	Jun. 19, 2015	May. 01, 2015	Jun. 30, 2015	Dec. 31, 2014	Dec. 19, 2014
Line of Credit Facility [Line Items]
Increase in revolving facility capacity	$ 150.0
Line of Credit | Revolving Facility
Line of Credit Facility [Line Items]
Revolving Credit, maximum borrowing capacity	$ 1,650.0				$ 1,500.0
Revolving Credit, fair value of amount outstanding			$ 160.0	$ 0.0
Line of Credit | Revolving Facility | Trailing Four Quarters | Maximum
Line of Credit Facility [Line Items]
Leverage ratio		4.75 to 1.00
Line of Credit | Revolving Facility | Subsequent Two Fiscal Quarters | Maximum
Line of Credit Facility [Line Items]
Leverage ratio		4.25 to 1.00
Line of Credit | Revolving Facility | Any Fiscal Quarter Thereafter | Maximum
Line of Credit Facility [Line Items]
Leverage ratio		3.75 to 1.00