Schedule II (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010		Dec. 31, 2009
Allowance for doubtful accounts receivable:
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 11,005	$ 11,833	$ 11,847		$ 11,930
Changes to Expense	(18)	(14)	(76)
Deductions‑ Write-offs	(810)	0	(7)
Balance at End of Year	11,005	11,833	11,847		11,930
Valuation/Allowance for deferred tax assets:
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	41,271	38,742	85,755		197,407
Changes to Expense	2,935	(47,013)	(111,652)	[1]
Deductions‑ Write-offs	(406)	0	0
Balance at End of Year	$ 41,271	$ 38,742	$ 85,755		$ 197,407

[1] Includes a tax benefit of $116.7 million attributable to the release of valuation allowances, as disclosed in Note 12 of the consolidated financial statements.