Geographical Operating Information (Details) (USD $)	3 Months Ended									12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011		Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Geographic Operating Information [Line Items]
Operating Income (Loss)	$ 115,678,000	$ 113,174,000	$ 98,590,000	$ 84,009,000	$ 81,325,000	[1]	$ 108,310,000	$ 79,073,000	$ 87,578,000	$ 411,451,000	$ 356,286,000	$ 281,951,000
Assets	3,122,951,000				2,569,348,000					3,122,951,000	2,569,348,000
United States
Geographic Operating Information [Line Items]
Sales										1,467,000,000	1,378,000,000	1,228,000,000
Operating Income (Loss)										409,000,000	350,000,000	268,000,000
Assets	3,022,000,000				2,473,000,000					3,022,000,000	2,473,000,000
New Zealand
Geographic Operating Information [Line Items]
Sales										104,000,000	111,000,000	87,000,000
Operating Income (Loss)										2,000,000	6,000,000	14,000,000
Assets	101,000,000				95,000,000					101,000,000	95,000,000
All other countries
Geographic Operating Information [Line Items]
Sales										0	0	0
Operating Income (Loss)										0	0	0
Assets	$ 0				$ 1,000,000					$ 0	$ 1,000,000

[1] Fourth quarter 2011 included a pre-tax expense of $6.5 million ($4.1 million after tax) due to an increase in a disposition reserve.