Earnings per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Amounts attributable to common stockholders:
Income from continuing operations	$ 139,338	$ 88,186
Income (loss) from discontinued operations	19,332	(1,882)
Net income (numerator for diluted EPS)	158,670	86,304
Less: Preference stock dividends	(13)	(15)
Income attributable to common stockholders (numerator for basic EPS)	$ 158,657	$ 86,289
Denominator (in thousands):
Weighted average shares used in basic EPS	199,960	203,690
Effect of dilutive shares:
Preferred stock	2	2
Preference stock	398	455
Stock plans	312	48
Weighted-average shares used in diluted EPS	200,672	204,195
Basic earnings per share:
Income from continuing operations	$ 0.70	$ 0.43
Income (loss) from discontinued operations	$ 0.10	$ (0.01)
Net income	$ 0.79	$ 0.42
Diluted earnings per share:
Income from continuing operations	$ 0.69	$ 0.43
Income (loss) from discontinued operations	$ 0.10	$ (0.01)
Net income	$ 0.79	$ 0.42
Anti-dilutive shares (in thousands):
Anti-dilutive shares not used in calculating diluted weighted-average shares	13,811	14,337