Fair Value (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value Disclosures [Abstract]
Short-term and Long-term Debt, Fair Value	$ 1,045.4pol_ShorttermandLongtermDebtFairValue	$ 1,010.3pol_ShorttermandLongtermDebtFairValue
Debt carrying value	$ 1,023.8	$ 988.9

Represents the aggregate of total long-term debt, including current maturities and short-term debt.

No definition available.

Name:	us-gaap_DebtLongtermAndShorttermCombinedAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant