Comprehensive Income (Changes in AOCL) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($)
Changes in AOCI by component (net of tax) [Roll Forward]
Balance as of beginning of period	$ (195.1)
Other comprehensive income (loss) before reclassifications	29.9
Amounts reclassified from AOCL	(1.3)
Net other comprehensive income (loss)	28.6
Balance as of end of period	(166.5)
Gains (Losses) on Cash Flow Hedges [Member]
Changes in AOCI by component (net of tax) [Roll Forward]
Balance as of beginning of period	5.6
Other comprehensive income (loss) before reclassifications	4.6
Amounts reclassified from AOCL	(3.8)
Net other comprehensive income (loss)	0.8
Balance as of end of period	6.4
Unrealized Gains on Available-for-Sale Securities [Member]
Changes in AOCI by component (net of tax) [Roll Forward]
Balance as of beginning of period	2.3
Other comprehensive income (loss) before reclassifications	0.1
Amounts reclassified from AOCL	0.0
Net other comprehensive income (loss)	0.1
Balance as of end of period	2.4
Defined Benefit Pension Plan Items [Member]
Changes in AOCI by component (net of tax) [Roll Forward]
Balance as of beginning of period	(130.0)
Other comprehensive income (loss) before reclassifications	(4.0)
Amounts reclassified from AOCL	2.5
Net other comprehensive income (loss)	(1.5)
Balance as of end of period	(131.5)
Foreign Currency Translation Adjustments [Member]
Changes in AOCI by component (net of tax) [Roll Forward]
Balance as of beginning of period	(73.0)
Other comprehensive income (loss) before reclassifications	29.2
Amounts reclassified from AOCL	0.0
Net other comprehensive income (loss)	29.2
Balance as of end of period	$ (43.8)