Commitments and Contingencies - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) employee collective_bargaining_agreement	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Rent expense for operating leases and other rental items	$ 191,800	$ 166,500	$ 149,000
Sublease rental income	$ 600	600	600
Number of collective bargaining agreements that are national or regional in scope | collective_bargaining_agreement	2
Restructuring expenses	$ 2,306	1,577	1,438
Restructuring reserve	$ 1,630	492	201
Minimum
Loss Contingencies [Line Items]
Number of employees | employee	33,000
Number of collective bargaining agreements between our individual subsidiaries and local unions | collective_bargaining_agreement	400
Surety Bond [Member]
Loss Contingencies [Line Items]
Aggregate estimated exposure	$ 1,100,000
Employee Severance [Member]
Loss Contingencies [Line Items]
Restructuring expenses	$ 2,306	$ 1,600	$ 1,400
Unionized Employees Concentration Risk [Member] | Workforce Subject to Collective Bargaining Arrangements [Member]
Loss Contingencies [Line Items]
Percentage of employees represented by unions	57.00%