Long-Term Debt (Subordinated Convertible Notes) (Details) - North America - USD ($)	Dec. 15, 2009	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Unamortized discount		$ 253,100,000	$ 255,600,000
Subordinated Convertible Notes Due 2029
Debt Instrument [Line Items]
Debt principal amount	$ 429,500,000.0
Nonconvertible debt borrowing rate on debt instrument issuance date	12.50%
Liability component of convertible notes	$ 162,900,000	429,500,000	429,500,000
Unamortized discount	266,600,000	$ 253,100,000	$ 255,600,000
Debt issuance costs	$ 14,500,000