Commitments and Contingencies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Apr. 23, 2010 subsidiary
Loss Contingencies [Line Items]
Rental expense	$ 87,300,000	$ 85,900,000	$ 89,900,000
Staffing Managers Case
Loss Contingencies [Line Items]
Number of subsidiaries | subsidiary				1
Allegations loss	0
Rodriguez Case
Loss Contingencies [Line Items]
Allegations loss	0
Gentry Case
Loss Contingencies [Line Items]
Allegations loss	$ 0