Equity Award Plans (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Equity award plans, additional disclosures
Amount of cash received from exercise of stock options	$ 161,000	$ 8,920,000	$ 17,134,000
2002 Plan
Equity Award Plans
Number of shares authorized	4,300,000
Stock based compensation expense	7,300,000	9,200,000	3,300,000
Income tax benefits in the entity's continuing operations recognized	2,700,000	3,200,000	1,200,000
Equity award plans, additional disclosures
Unrecognized compensation costs	7,100,000	12,600,000	2,300,000
Weighted average period over which unrecognized compensation costs will be recognized (in years)	1.7
Stock options
Summary of activity related to stock options during the year including awards applicable to discontinued operations
Outstanding at the beginning of the period (in shares)	495,324
Granted (in shares)	87,192
Exercised (in shares)	(26,163)
Forfeited or expired (in share)	(14,984)
Outstanding at the end of the period (in shares)	541,369	495,324
Exercisable
Exercisable at the end of the period (in shares)	418,879
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollar per share)	$ 43.13
Granted (in dollar per share)	$ 62.88
Exercised (in dollar per share)	$ 6.11
Forfeited or expired (in dollar per share)	$ 97.71
Outstanding at the end of the period (in dollar per share)	$ 46.58	$ 43.13
Exercisable at the end of the period (in dollar per share)	$ 38.09
Weighted Average Remaining Contractual Term
Outstanding at the end of the period (in years)	5.3
Exercisable at the end of the period (in years)	4.3
Aggregate Intrinsic Value
Outstanding at the end of the period	3,808,000
Exercisable at the end of the period	3,811,000
Weighted average assumptions used to determine the grant-date fair value of options granted
Risk free interest rate (as a percent)	0.85%	0.88%	2.22%
Dividend yield (as a percent)	0.55%	0.52%	0.75%
Expected life (in years)	4.95	2.46	5.10
Volatility (as a percent)	75.79%	57.51%	69.64%
Equity award plans, additional disclosures
Weighted average grant-date fair values of stock options granted (in dollar per share)	$ 36.97	$ 81.82	$ 46.43
Amount of cash received from exercise of stock options	200,000	8,900,000	17,100,000
Intrinsic value of stock options exercised	1,400,000	24,200,000	43,100,000
Restricted stock units
Summary of activity related to nonvested restricted stock units, including awards applicable to discontinued operations
Outstanding at the beginning of the period (in shares)	163,247
Granted (in shares)	65,312
Vested (in shares)	(43,888)
Forfeited or expired (in share)	(35,400)
Outstanding at the end of the period (in shares)	149,271	163,247
Aggregate Intrinsic Value
Outstanding at the end of the period	5,356,000
Weighted Average Remaining Contractual Term in Years
Outstanding at the end of the period (in years)	1.11
Equity award plans, additional disclosures
Weighted average grant-date fair values of nonvested restricted stock units granted (in dollar per share)	$ 63.17	$ 133.15	$ 82.30
Intrinsic value of restricted stock vested	1,600,000	7,700,000	11,000,000
Fair value of restricted stock units vested	500,000	4,900,000	5,800,000
Employee stock purchase plan
Equity Award Plans
Number of shares authorized	3,500,000
Stock based compensation expense	$ 500,000	$ 400,000	$ 200,000
Employee Stock Purchase Plan
Employer contribution, as a percentage of participant's actual payroll deduction	15.00%
Employer contribution after five years of continuous participation , as a percentage of participant's actual payroll deduction	20.00%
Period of continuous employee participation required to receive employer contribution of 20% of participant's actual payroll deduction (in years)	5
Number of shares purchased under the plan	86,200	29,500	20,000