Segment and Geographical Information - Schedule of Geographical Operating Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 166,146	$ 200,890	$ 245,906	$ 203,196	$ 239,722	$ 184,419	$ 200,964	$ 194,491	$ 816,138	$ 819,596	$ 815,915
Operating Income									170,068	215,491	255,777
Identifiable Assets	2,780,666				2,858,481				2,780,666	2,858,481
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									390,396	419,402	528,345
Operating Income									83,357	138,528	220,703
Identifiable Assets	2,282,480				2,331,230				2,282,480	2,331,230
New Zealand
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									425,742	400,194	287,570
Operating Income									86,711	76,963	$ 35,074
Identifiable Assets	$ 498,186				$ 527,251				$ 498,186	$ 527,251