Joint Venture Investment (Details) - a a in Millions	Dec. 31, 2017	Mar. 31, 2016	Mar. 03, 2016	Apr. 30, 2013	Apr. 04, 2013
Noncontrolling Interest [Line Items]
Ownership percentage by parent		77.00%	77.00%	65.00%	65.00%
Acres of timberland owned	2.6
Noncontrolling interest ownership percentage by noncontrolling owners				23.00%
Matariki Forestry Group
Noncontrolling Interest [Line Items]
Ownership percentage by parent	77.00%
Acres of timberland owned	0.4
Noncontrolling interest ownership percentage by noncontrolling owners	23.00%