Equity Method Investments - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Joint-venture interest	50.00%		50.00%
Increase to carrying value of equity method investment	$ 20.4		$ 20.4
Equity Method Investee
Schedule of Equity Method Investments [Line Items]
Accounts receivable from equity method investments	33.9		33.9		$ 31.9
Wendy's Company TIMWEN Partnership | Tim Hortons
Schedule of Equity Method Investments [Line Items]
Cash distributions	2.9	$ 3.0	5.8	$ 5.4
Contingent rent expense	5.0	$ 4.9	9.5	$ 9.4
Carrols Restaurant Group, Inc.
Schedule of Equity Method Investments [Line Items]
Quoted market price	$ 139.8		$ 139.8
BK Brasil
Schedule of Equity Method Investments [Line Items]
Joint-venture interest	10.10%		10.10%
Quoted market price	$ 91.3		$ 91.3
Other assets
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 264.9		$ 264.9		$ 155.1
Canada | Wendy's Company TIMWEN Partnership
Schedule of Equity Method Investments [Line Items]
Joint-venture interest	50.00%		50.00%
United States | Carrols Restaurant Group, Inc.
Schedule of Equity Method Investments [Line Items]
Joint-venture interest	20.50%		20.50%