Summary of Significant Accounting Policies (Details 5) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 year	Mar. 31, 2011 year
Share-Based Compensation, aggregate disclosures
Employee stock-based awards, unrecognized compensation costs on nonvested awards	$ 55,291
Employee stock-based awards, unrecognized compensation costs on nonvested awards, weighted average period of recognition (in years)	2.8
Stock Options
Employee stock-based awards
Weighted average fair value of options granted (in dollars per share)	$ 7.00	$ 7.34
Weighted average assumptions used for grants
Expected volatility (as a percent)	33.80%	33.40%
Risk-free interest rate (as a percent)	1.23%	2.51%
Expected dividend yield (as a percent)	3.00%	3.00%
Expected life of the option (in years)	6.3	6.3
Summary of option activity
Options outstanding balance, beginning of period (in shares)	7,118,458
Options granted (in shares)	21,472
Options exercised (in shares)	(103,868)
Options forfeited (in shares)	(90,076)
Options expired (in shares)	(9,510)
Options outstanding balance, end of period (in shares)	6,936,476
Options exercisable balance (in shares)	4,082,790
Options expected to vest (in shares)	2,643,329
Weighted Average Exercise Price
Weighted average exercise price, options outstanding balance beginning of period (in dollars per share)	$ 25.73
Weighted average exercise price, options granted (in dollars per share)	$ 28.86
Weighted average exercise price, options exercised (in dollars per share)	$ 20.47
Weighted average exercise price, options forfeited (in dollars per share)	$ 25.92
Weighted average exercise price, options expired (in dollars per share)	$ 30.33
Weighted average exercise price, options outstanding balance end of period (in dollars per share)	$ 25.81
Weighted average exercise price, options exercisable (in dollars per share)	$ 25.48
Weighted average exercise price, options expected to vest (in dollars per share)	$ 26.31
Weighted average remaining contractual term
Weighted average remaining contractual term, options outstanding (in years)	6.47
Weighted average remaining contractual term, options exercisable (in years)	5.57
Weighted average remaining contractual term, options expected to vest (in years)	7.75
Aggregate intrinsic value
Aggregate intrinsic value, options outstanding	23,729
Aggregate intrinsic value, options exercisable	15,598
Aggregate intrinsic value of stock options exercised
Aggregate intrinsic value of stock options exercised	1,064	6,047
Award Vesting
Aggregate intrinsic value, options expected to vest	7,504
Stock Options | Director
Employee stock-based awards
Award vesting period (in years)	1 year
Majority of stock options
Employee stock-based awards
Award vesting period (in years)	5 years
Contractual term of awards	P10Y
Certain options beginning in 2011
Employee stock-based awards
Award vesting period (in years)	3 years
Contractual term of awards	P10Y
Certain options as a percentage of total outstanding options	11.30%
A portion of stock options effective 2007
Employee stock-based awards
Award vesting period (in years)	10 years
Contractual term of awards	P12Y
Certain options as a percentage of total outstanding options	7.50%
Employee Stock Purchase Plan
Employee stock-based awards
Remaining number of shares available for grant	399,761
Employee Stock Purchase Plan
Employee stock purchase plan, number of offering periods	2
Employee stock purchase plan, duration of offering periods (in months)	6
Employee stock purchase plan, maximum employee subscription rate percent (as a percent)	15.00%
Percentage of market price for the purchase of shares	95.00%
Restricted Stock and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Non-vested at the beginning of the period (in shares)	610,951
Granted (in shares)	655,809
Vested (in shares)	(139,477)
Forfeited (in shares)	(11,550)
Non-vested at the end of the period (in shares)	1,115,733
Weighted average grant date fair value
Weighted average grant date fair value, non-vested, beginning of period (in dollars per share)	$ 28.85
Weighted average grant date fair value, granted (in dollars per share)	$ 28.86
Weighted average grant date fair value, vested (in dollars per share)	$ 28.36
Weighted average grant date fair value, forfeited (in dollars per share)	$ 28.75
Weighted average grant date fair value, non-vested, end of period (in dollars per share)	$ 28.92
Restricted Stock and Restricted Stock Units | Maximum
Employee stock-based awards
Award vesting period (in years)	5 years
Restricted Stock and Restricted Stock Units | Minimum
Employee stock-based awards
Award vesting period (in years)	3 years
PUs Original Awards
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Non-vested at the beginning of the period (in shares)	112,749
Granted (in shares)	221,781
Vested (in shares)	(96,120)
Forfeited (in shares)	(291)
Non-vested at the end of the period (in shares)	238,119
PUs Adjustment
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Granted (in shares)	12,012
Vested (in shares)	(1,938)
Non-vested at the end of the period (in shares)	10,074
Performance units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Non-vested at the beginning of the period (in shares)	112,749
Granted (in shares)	221,781
Vested (in shares)	(98,058)
Forfeited (in shares)	(291)
Non-vested at the end of the period (in shares)	248,193
Weighted average grant date fair value
Weighted average grant date fair value, non-vested, beginning of period (in dollars per share)	$ 29.06
Weighted average grant date fair value, granted (in dollars per share)	$ 28.87
Weighted average grant date fair value, vested (in dollars per share)	$ 28.46
Weighted average grant date fair value, forfeited (in dollars per share)	$ 28.11
Weighted average grant date fair value, non-vested, end of period (in dollars per share)	$ 29.11
Total fair value of shares or units vested	2,825
Performance units disclosure
Performance period (in years)	1
Period of anniversary from the date of grant (in years)	1
Qualifying age for grant of performance units (in years)	55
Qualifying service period (in years)	10 years
Percentage of achievement of the predefined revenue and ROIC targets	100.00%
Closing market price of common stock (in dollars per share)	$ 28.80
Award vesting period, minimum (in years)	P1Y
Award vesting period, maximum (in years)	P3Y
Performance units | Maximum
Performance units disclosure
Percentage payout rate	150.00%
Performance units | Minimum
Performance units disclosure
Percentage payout rate	0.00%
Restricted Stock Units
Weighted average grant date fair value
Total fair value of shares or units vested	$ 3,979