Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments And Contingencies Disclosure [Abstract]

Future Minimum Rental Commitments Under Non-cancellable Operating Leases

At December 31, 2017, future minimum rental commitments under non-cancellable operating leases are as follows ($ in thousands):

Year	Amount
2018		12,031
2019		10,436
2020		6,642
2021		5,197
2022		5,039
Thereafter		28,518
Total	$	67,863