Subsequent Event (Details) - Pending tax adjustment	12 Months Ended
	Dec. 31, 2017 USD ($)
Subsequent Event [Line Items]
Subsequent events date	Feb. 13, 2018
Subsequent event description	Revenue Procedure 2018-17 (the “Rev. Proc.) prevents changes to the annual accounting periods of certain foreign corporations in 2017 under either the existing automatic or general procedures if such change could result in the avoidance, reduction, or delay of the deemed Repatriation Tax.
Revenue Proceedure 2018-17, estimate, one-time related tax expense	$ 48,000,000