Significant Risks and Uncertainties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Insurance Matters [Abstract]
Insurance deductible per incident	$ 55.0
Minimum business interruption period (in days)	60 days
February 2011 West Storage Incident [Member]
Loss Contingencies [Line Items]
Gains related to property damage proceeds		$ 95.0	$ 15.0
Proceeds from property damage insurance recoveries		$ 95.0	$ 15.0