Derivative Instruments, Foreign Exchange Contracts (Details) - Foreign Exchange Contract [Member] € in Millions, ¥ in Millions, CAD in Millions, AUD in Millions	9 Months Ended
	Sep. 30, 2017 AUD	Sep. 30, 2017 CAD	Sep. 30, 2017 EUR (€)	Sep. 30, 2017 JPY (¥)	Dec. 31, 2016 AUD	Dec. 31, 2016 CAD	Dec. 31, 2016 EUR (€)	Dec. 31, 2016 JPY (¥)
Derivative [Line Items]
Foreign exchange contract outstanding	AUD 0.2	CAD 0.0	€ 0.2	¥ 212.5	AUD 0.6	CAD 0.5	€ 0.1	¥ 281.4
Expiration date of contract	Dec. 31, 2018