Restructuring - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended		30 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2018 store	Dec. 31, 2017 store	Jun. 30, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Total Restructuring Expenses	$ (882)	$ 13,445	$ 24	$ 13,772
Restructuring Program 2016 and 2017
Restructuring Cost and Reserve [Line Items]
Total Restructuring Expenses							$ 38,300
Restructuring Program 2017
Restructuring Cost and Reserve [Line Items]
Expected additional restructuring charges	1,000		1,000				$ 1,000
Gain on Sale of Closed Store Properties
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, number of store closures | store						139
Total Restructuring Expenses	$ 0	$ 0	(327)	$ 0
Gain on Sale of Closed Store Properties | Scenario, Forecast
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, number of store closures | store					7
Maximum
Restructuring Cost and Reserve [Line Items]
Total Restructuring Expenses			$ 100