Stockholders' Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2002
Class of Stock [Line Items]
Common stock shares repurchased (in shares)	13,948,687	8,620,689	21,721,959
Aggregate cost of common stock repurchased	$ 150,000	$ 150,000	$ 275,000
Warrants issued				8,823,529
Permitted stock repurchase capacity under credit facility	$ 174,548
Shares reserved (in shares)	66,659,311
Class B Convertible Common Stock [Member]
Class of Stock [Line Items]
Voting rights per share	10
Conversion feature	one-for-one
Shares reserved (in shares)	12,129,227
Common Stock [Member]
Class of Stock [Line Items]
Voting rights per share	1
Common stock options outstanding [Member]
Class of Stock [Line Items]
Shares reserved (in shares)	109,000
Restricted stock units outstanding [Member]
Class of Stock [Line Items]
Shares reserved (in shares)	1,316,000
Available to grant 2007 Stock Incentive Program - [Member]
Class of Stock [Line Items]
Shares reserved (in shares)	1,140,000
Phantom stock units outstanding [Member]
Class of Stock [Line Items]
Shares reserved (in shares)	97,000
Phantom stock units available to grant [Member]
Class of Stock [Line Items]
Shares reserved (in shares)	85,000
Exchangeable Unsecured Notes, Due 2102 [Member]
Class of Stock [Line Items]
Shares reserved (in shares)	6,176,471
Convertible Senior Debentures, Due 2040 [Member]
Class of Stock [Line Items]
Shares reserved (in shares)	22,285,258
Number of shares debentures are convertible into (in shares)	19,809,103
Convertible Senior Debentures, Due 2041 [Member]
Class of Stock [Line Items]
Shares reserved (in shares)	8,870,490
Number of shares debentures are convertible into (in shares)	7,884,885
Convertible Senior Debentures 2042 [Member]
Class of Stock [Line Items]
Shares reserved (in shares)	14,450,865
Number of shares debentures are convertible into (in shares)	12,704,055