Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Minimum Rental Commitments Under Non-Cancelable Leases

The approximate minimum rental commitments for 2018 and thereafter under non-cancelable leases in effect at December 31, 2017 were as follows (in thousands):

2018	$	85,484
2019	73,763
2020	64,221
2021	47,107
2022	35,535
Thereafter	64,042
	$	370,152