Summary of Significant Accounting Policies (Details 5) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012 year	Jun. 30, 2011	Jun. 30, 2012 year	Jun. 30, 2011 year
Share-Based Compensation, aggregate disclosures
Employee stock-based awards, unrecognized compensation costs on nonvested awards	$ 52,757		$ 52,757
Employee stock-based awards, unrecognized compensation costs on nonvested awards, weighted average period of recognition (in years)			2.6
Stock Options
Employee stock-based awards
Weighted average fair value of options granted (in dollars per share)			$ 7.00	$ 7.43
Weighted average assumptions used for grants
Expected volatility (as a percent)			33.80%	33.40%
Risk-free interest rate (as a percent)			1.24%	2.47%
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)			(412,728)
Options forfeited (in shares)			(171,402)
Options expired (in shares)			(28,291)
Options outstanding balance, end of period (in shares)	6,527,509		6,527,509
Options exercisable balance (in shares)	4,236,162		4,236,162
Options expected to vest (in shares)	2,118,795		2,118,795
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		$ 28.86
Weighted average exercise price, options exercised (in dollars per share)	$ 23.48		$ 23.48
Weighted average exercise price, options forfeited (in dollars per share)	$ 25.83		$ 25.83
Weighted average exercise price, options expired (in dollars per share)	$ 33.03		$ 33.03
Weighted average exercise price, options outstanding balance end of period (in dollars per share)	$ 25.85		$ 25.85
Weighted average exercise price, options exercisable (in dollars per share)	$ 25.69		$ 25.69
Weighted average exercise price, options expected to vest (in dollars per share)	$ 26.16		$ 26.16
Weighted average remaining contractual term
Weighted average remaining contractual term, options outstanding (in years)	6.24		6.24
Weighted average remaining contractual term, options exercisable (in years)			5.48
Weighted average remaining contractual term, options expected to vest (in years)			7.63
Aggregate intrinsic value
Aggregate intrinsic value, options outstanding	47,476		47,476
Aggregate intrinsic value, options exercisable	31,678		31,678
Aggregate intrinsic value of stock options exercised
Aggregate intrinsic value of stock options exercised	2,308	22,862	3,372	28,909
Award Vesting
Aggregate intrinsic value, options expected to vest	14,594		14,594
Stock Options | Director
Employee stock-based awards
Award vesting period			1 year
Majority of stock options
Employee stock-based awards
Award vesting period			5 years
Contractual term of awards			P10Y
Certain options beginning in 2011
Employee stock-based awards
Award vesting period			3 years
Contractual term of awards			P10Y
Certain options as a percentage of total outstanding options	11.80%		11.80%
A portion of stock options effective 2007
Employee stock-based awards
Award vesting period			10 years
Contractual term of awards			P12Y
Certain options as a percentage of total outstanding options	7.50%		7.50%
Employee Stock Purchase Plan
Employee stock-based awards
Remaining number of shares available for grant	311,089		311,089
Employee Stock Purchase Plan
Employee stock purchase plan, number of offering periods	2		2
Employee stock purchase plan, duration of offering periods			180 days
Employee stock purchase plan, maximum employee subscription rate percent (as a percent)	15.00%		15.00%
Percentage of market price for the purchase of shares			95.00%
Employee stock purchase plan, shares issued in period			88,672	82,267
Restricted Stock and Restricted Stock Units
Dividends accrued
Accrued cash dividends on RSUs			34
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)			781,815
Vested (in shares)			(204,794)
Forfeited (in shares)			(26,110)
Non-vested at the end of the period (in shares)	1,161,862		1,161,862
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)			$ 29.48
Weighted average grant date fair value, vested (in dollars per share)			$ 29.12
Weighted average grant date fair value, forfeited (in dollars per share)	$ 28.96		$ 28.96
Weighted average grant date fair value, non-vested, end of period (in dollars per share)	$ 29.22		$ 29.22
Restricted Stock and Restricted Stock Units | Minimum
Employee stock-based awards
Award vesting period			3 years
Restricted Stock and Restricted Stock Units | Maximum
Employee stock-based awards
Award vesting period			5 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)			(124,914)
Forfeited (in shares)			(3,381)
Non-vested at the end of the period (in shares)	206,235		206,235
PUs Adjustment
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Granted (in shares)			12,012
Vested (in shares)			(5,013)
Non-vested at the end of the period (in shares)	6,999		6,999
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)			233,793
Vested (in shares)			(129,927)
Forfeited (in shares)			(3,381)
Non-vested at the end of the period (in shares)	213,234		213,234
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)			$ 29.47
Weighted average grant date fair value, forfeited (in dollars per share)	$ 28.11		$ 28.11
Weighted average grant date fair value, non-vested, end of period (in dollars per share)	$ 28.61		$ 28.61
Total fair value of shares or units vested	1,233		4,058
Performance units disclosure
Performance period			1 year
Period of anniversary from the date of grant			1 year
Qualifying age for grant of performance units (in years)	55	55	55	55
Qualifying service period (in years)	10 years	10 years	10 years	10 years
Percentage of achievement of the predefined revenue and ROIC targets	100.60%		100.60%
Closing market price of common stock (in dollars per share)	$ 32.96		$ 32.96
Award vesting period, minimum			P1Y
Award vesting period, maximum			P3Y
Performance units | Minimum
Performance units disclosure
Percentage payout rate	0.00%	0.00%	0.00%	0.00%
Performance units | Maximum
Performance units disclosure
Percentage payout rate	150.00%	150.00%	150.00%	150.00%
Restricted Stock Units
Weighted average grant date fair value
Total fair value of shares or units vested	1,985	462	5,964	462
Restricted Stock Plan
Weighted average grant date fair value
Total fair value of shares or units vested	$ 1	$ 13	$ 1	$ 13