Sale-Leasebacks of Real Estate - Narrative (Details) $ in Thousands		1 Months Ended			12 Months Ended
	Sep. 15, 2016 USD ($)	Jul. 31, 2013 warehouse	Sep. 30, 2010 USD ($)	Sep. 30, 2007 USD ($) warehouse extension	Dec. 31, 2018 USD ($) warehouse	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2011
Sale Leaseback Transaction [Line Items]
Percentage of useful life where control maintained				90.00%
Assets under sale-leaseback agreements					$ 80,300	$ 90,500	$ 91,600
Sale-leaseback financing obligations					$ 118,920	121,516
Gross proceeds from sale-leaseback transaction				$ 170,700
Annual rent increase under sale-leaseback transaction		0.50%		1.75%
Number of extensions under sale-leaseback transaction | extension				4
Extension period under sale-leaseback transaction				5 years				5 years
Number of units where agreement was amended | warehouse		6
Number of warehouses | warehouse		11		11	11
Payments for purchase option under sale-leaseback transaction	$ 3,500
Interest expense	$ 300				$ 93,312	114,898	$ 119,552
1 warehouse – 2010
Sale Leaseback Transaction [Line Items]
Purchase option transferred			$ 18,300
Lease agreement term			20 years
Consideration to be used toward improvements			$ 1,000
Percentage of useful life where control maintained			90.00%
Purchase price option percentage			95.00%
Assets under sale-leaseback agreements			$ 18,200
Receivable for improvements			1,000
Sale-leaseback financing obligations			$ 19,200		$ 19,265	$ 19,457
Number of warehouses | warehouse					1
Minimum
Sale Leaseback Transaction [Line Items]
Lease agreement term				10 years
Maximum
Sale Leaseback Transaction [Line Items]
Lease agreement term				20 years