Income Taxes, Schedule of Statutory Tax Rates (Details)		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statutory Tax Rates
Applicable statutory income tax rate (percent)		29.80%	27.10%	32.80%
U.S. [Member]
Statutory Tax Rates
Applicable statutory income tax rate (percent)	[1]	35.00%	35.00%	35.00%
Canada [Member]
Statutory Tax Rates
Applicable statutory income tax rate (percent)		15.00%	15.00%	15.00%
U.K. [Member]
Statutory Tax Rates
Applicable statutory income tax rate (percent)		19.00%	20.25%	20.25%
Ireland [Member]
Statutory Tax Rates
Applicable statutory income tax rate (percent)		13.00%	12.50%	12.50%
Aruba [Member]
Statutory Tax Rates
Applicable statutory income tax rate (percent)	[2]		7.00%	7.00%

[1] Statutory income tax rate was reduced to 21 percent effective January 1, 2018 as described in “Tax Reform” above.

[2] Statutory income tax rate applicable through the date of the Aruba Disposition as described in Note 2.