Debt Interest Rates, Interest Rate Swaps and Contingent Debt (Details)	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Debt, Weighted Average Interest Rate	5.02%	4.95%

Weighted average interest rate of debt outstanding.

No definition available.

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant