Summary of Significant Accounting Policies, Derivative Instruments, Foreign Exchange Contracts (Details) € in Millions, ¥ in Millions, £ in Millions, CAD in Millions, AUD in Millions	12 Months Ended
	Dec. 31, 2016 CAD	Dec. 31, 2016 EUR (€)	Dec. 31, 2016 AUD	Dec. 31, 2016 JPY (¥)	Dec. 31, 2015 CAD	Dec. 31, 2015 EUR (€)	Dec. 31, 2015 AUD	Dec. 31, 2015 GBP (£)
Derivative [Line Items]
Expiration date of contract	Dec. 20, 2018
Foreign Exchange Contract [Member] | Canada, Dollars
Derivative [Line Items]
Foreign exchange contract outstanding | CAD	CAD 0.5				CAD 1.3
Foreign Exchange Contract [Member] | Japan, Yen
Derivative [Line Items]
Foreign exchange contract outstanding | ¥				¥ 281.4
Foreign Exchange Contract [Member] | Pounds [Member]
Derivative [Line Items]
Foreign exchange contract outstanding | £								£ 0.5
Foreign Exchange Contract [Member] | Euro [Member]
Derivative [Line Items]
Foreign exchange contract outstanding | €		€ 0.1				€ 2.1
Foreign Exchange Contract [Member] | Australian Dollars [Member]
Derivative [Line Items]
Foreign exchange contract outstanding | AUD			AUD 0.6				AUD 0.4