Commitments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) lease	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Commitments
2018	$ 11,792
2019	6,522
2020	6,277
2021	4,017
2022	3,562
Thereafter	6,245
Total	38,415
Commitments:
2018	22,625
2019	16,739
2020	16,050
2021	13,522
2022	12,987
Thereafter	162,112
Total	244,035
Pension contribution requirements in next fiscal year	$ 2,900
Matariki Crown Forest Licenses
Commitments:
Future minimum payments included, years	20 years
Termination notice	35 years
Renewal term	1 year
Number of leases under termination notice | lease	3
Number of fixed term forest leases expiring | lease	2
Operating Leases
Operating Leased Assets [Line Items]
Lease expenses	$ 1,992	$ 2,049	$ 2,349
Leases:
2018	1,135
2019	914
2020	733
2021	639
2022	608
Thereafter	635
Total	4,664
Timber Leases
Operating Leased Assets [Line Items]
Lease expenses	10,731	$ 10,710	$ 11,342
Leases:
2018	9,698
2019	9,303
2020	9,040
2021	8,866
2022	8,817
Thereafter	155,232
Total	$ 200,956
Timber Leases | United States | Minimum
Operating Leased Assets [Line Items]
Lessee leasing arrangements, operating leases, term of contract (in years)	30 years
Timber Leases | United States | Maximum
Operating Leased Assets [Line Items]
Lessee leasing arrangements, operating leases, term of contract (in years)	65 years
Timber Leases | New Zealand | Minimum
Operating Leased Assets [Line Items]
Lessee leasing arrangements, operating leases, term of contract (in years)	30 years
Timber Leases | New Zealand | Maximum
Operating Leased Assets [Line Items]
Lessee leasing arrangements, operating leases, term of contract (in years)	99 years