Commitments and contingent liabilities (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Future Minimum Lease Payments Under Noncancelable Operating Leases

Future minimum lease payments as of December 31, 2017 under noncancellable operating leases are as follows:

	Future Lease Payments
	(Dollars in thousands)
2018	$	30,262
2019	26,531
2020	21,355
2021	18,186
2022	15,774
2023 and thereafter	27,167