Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of Rent Expense under Operating Leases

Rent expense under operating leases for the years ended December 31 aggregated (in thousands):

	2017		2016		2015
Rent expense	$	11,964	$	13,652	$	13,959

Schedule of Future Minimum Lease Payments under Non-Cancelable Operating Leases

Future minimum lease payments under these noncancelable operating leases as of December 31, 2017 are as follows (in thousands):

	2018	2019	2020	2021	2022	Thereafter
Future minimum lease payments	11,072	9,274	6,521	4,773	3,817	5,211