Geographical Operating Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Total Sales	$ 520,242	$ 384,784	$ 409,077	$ 393,719	$ 412,660	$ 386,163	$ 348,096	$ 336,571	$ 1,707,822	$ 1,483,490	$ 1,420,960
Operating Income									422,814	400,560	357,294
Identifiable Assets	3,685,501				3,122,951				3,685,501	3,122,951
Geographic Concentration Risk [Member] | United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total Sales									1,428,000	1,379,000	1,310,000
Operating Income									394,000	399,000	351,000
Identifiable Assets	3,077,000				3,022,000				3,077,000	3,022,000
Geographic Concentration Risk [Member] | New Zealand [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total Sales									280,000	104,000	111,000
Operating Income									29,000	2,000	6,000
Identifiable Assets	$ 609,000				$ 101,000				$ 609,000	$ 101,000