Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of rent expense associated with operating leases

The table below presents rent expense associated with facility, vehicle and equipment operating leases for the past three years (in thousands):

2017		2016		2015
$	66,161	$	63,940	$	60,129

Future minimum lease payments related to non-cancelable operating leases

The table below sets forth the approximate future minimum lease payments as of December 31, 2017 related to non-cancelable facility operating leases and the non-cancelable portion of certain equipment operating leases with initial terms of one year or more (in thousands):

2018	$	55,874
2019	49,540
2020	42,524
2021	30,756
2022	21,612
Thereafter	21,423