Retirement Benefit Plans (Breakdown of amounts in accumulated other comprehensive income expected to be amortized into net periodic benefit cost) (Details) (New) $ in Millions	12 Months Ended
Dec. 31, 2016 USD ($)
Retirement Plans [Member]
Prior service cost/(credit)	$ 0.1
Net actuarial loss/(gain)	3.1
Total	3.2
Medical Plan [Member]
Prior service cost/(credit)	0.0
Net actuarial loss/(gain)	0.0
Total	$ 0.0

Amount included in accumulated other comprehensive income (AOCI) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position, including gain (loss), prior service cost (credit), and transition asset (obligation).

No definition available.

Name:	us-gaap_DefinedBenefitPlanAmountToBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration