Restructuring - Narrative (Details) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended	21 Months Ended
	Dec. 31, 2017 store	Sep. 30, 2017 USD ($) store	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Store	Sep. 30, 2016 USD ($)	Dec. 31, 2016 Store	Sep. 30, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 845	$ 4,658	$ 14,617	$ 4,658
Restructuring Program 2016 and 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges							$ 34,800
Restructuring Program 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges		900
Expected additional restructuring charges		1,000		1,000			1,000
Restructuring Program 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges		(100)		13,700
Expected additional restructuring charges		$ 1,000		$ 1,000			$ 1,000
Facility Closing | Restructuring Program 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, number of store closures | store		5
Facility Closing | Restructuring Program 2016
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, number of store closures | Store				66		56
Contractual Lease Obligations
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 694		$ 12,676
Contractual Lease Obligations | Restructuring Program 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges		400
Contractual Lease Obligations | Restructuring Program 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges		300
Fixed Asset Impairment/Other | Restructuring Program 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges		400
Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges				$ 1,306
Severance | Restructuring Program 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ (400)
Scenario, Forecast | Facility Closing | Restructuring Program 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, number of store closures | store	12
Scenario, Forecast | Facility Closing | Restructuring Program 2016
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, number of store closures | store	3