Debt Additional Information (Details) (USD $)	3 Months Ended				9 Months Ended							3 Months Ended	9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014 Senior Notes 3.65% Senior Notes, due September 2024	Sep. 05, 2014 Senior Notes 3.65% Senior Notes, due September 2024	Dec. 31, 2013 Senior Notes 3.65% Senior Notes, due September 2024	Sep. 30, 2014 Write-Off of Deferred Financing Costs	Sep. 30, 2014 Write-Off of Deferred Financing Costs
Debt Instrument [Line Items]
Debt, face amount										$ 400,000,000
Stated interest rate									3.65%	3.65%	0.00%
Repayments of Long-term Debt					589,900,000
Financing costs paid					3,209,000		8,220,000
Cash payments paid for interest					50,000,000		21,000,000
Repayments of Long-term Debt [Abstract]
Remainder of 2014	1,600,000				1,600,000
2015	6,500,000				6,500,000
2016	6,500,000				6,500,000
2017	6,500,000				6,500,000
2018	221,500,000				221,500,000
2019	6,500,000				6,500,000
2020 and thereafter	2,100,000,000				2,100,000,000
Amortization of net (loss) gain on treasury lock	1,400,000		1,400,000		4,200,000		4,200,000
Amortization of financing costs	2,000,000		2,900,000		2,900,000		3,300,000
Write-off of deferred financing costs	(23,111,000)	[1],[2]	(11,850,000)	[3]	(65,311,000)	[1],[2]	(30,333,000)	[3]				1,500,000	1,500,000
Book value of fixed rate debt	1,646,900,000				1,646,900,000
Book value of variable rate debt	710,100,000				710,100,000
Long-term debt (fixed-rate debt), fair value	$ 1,713,100,000				$ 1,713,100,000

[1] Includes $1.5 million of expense related to the write-off of deferred financing costs in connection with the debt refinancing discussed in Note 10, Debt.

[2] On October 25, 2013, we acquired Boise. The 2014 results include Boise for the full period.

[3] Includes $2.7 million of acquisition-related costs primarily related to financing the acquisition of Boise.