Long-Term Obligations (Schedule of Shareholder Loans) (Details) GHS in Millions, $ in Millions, UGX in Billions	Dec. 31, 2017 USD ($)	Dec. 31, 2017 GHS	Dec. 31, 2017 UGX	Jan. 01, 2017 USD ($)	Jan. 01, 2017 UGX	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Long-term debt	$ 20,205.1
Unsecured Debt
Debt Instrument [Line Items]
Long-term debt	246.1					$ 286.0
Unsecured Debt | Ghana Loan
Debt Instrument [Line Items]
Long-term debt	$ 66.5	GHS 300.9				71.0
Long-term debt, stated interest rate	21.87%	21.87%	21.87%
Unsecured Debt | Uganda Loan
Debt Instrument [Line Items]
Long-term debt	$ 34.1		UGX 124.1	$ 80.0		$ 80.1
Long-term debt, stated interest rate	16.80%	16.80%	16.80%	16.80%	16.80%
Unsecured Debt | Uganda Replacement Loan
Debt Instrument [Line Items]
Long-term debt				$ 31.8	UGX 114.5