Segment and Geographical Information - Geographical Operating Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 220,464	$ 171,421	$ 261,550	$ 134,843	$ 137,111	$ 151,657	$ 115,801	$ 140,305	$ 788,278	$ 544,874	$ 603,521
Operating Income									255,777	77,784	98,289
Identifiable Assets	2,685,760				2,315,938				2,685,760	2,315,938
Geographic Operating Information | United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									507,391	302,074	317,422
Operating Income									220,703	73,749	87,116
Identifiable Assets	2,181,658				1,823,137				2,181,658	1,823,137
Geographic Operating Information | New Zealand
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									280,887	242,800	286,099
Operating Income									35,074	4,035	$ 11,173
Identifiable Assets	$ 504,102				$ 492,801				$ 504,102	$ 492,801