Summary of Significant Accounting Policies (Details 5) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Share-Based Compensation, aggregate disclosures
Employee stock-based awards, unrecognized compensation costs on nonvested awards	$ 65,956
Employee stock-based awards, unrecognized compensation costs on nonvested awards, weighted average period of recognition	2 years 2 months 12 days
Stock Options
Employee stock-based awards
Weighted average fair value of options granted (in dollars per share)	$ 7.69	$ 7.00
Weighted average assumptions used for grants
Expected volatility (as a percent)	33.80%	33.80%
Risk-free interest rate (as a percent)	1.13%	1.23%
Expected dividend yield (as a percent)	3.00%	3.00%
Expected life of the option	6 years 3 months 18 days	6 years 3 months 18 days
Summary of option activity
Options outstanding balance, beginning of period (in shares)	5,908,102
Options granted (in shares)	261,698
Options exercised (in shares)	(413,206)
Options forfeited (in shares)	(52,931)
Options expired (in shares)	(1,758)
Options outstanding balance, end of period (in shares)	5,701,905
Options exercisable balance (in shares)	3,678,624
Options expected to vest (in shares)	1,901,202
Weighted Average Exercise Price
Weighted average exercise price, options outstanding balance beginning of period (in dollars per share)	$ 23.29
Weighted average exercise price, options granted (in dollars per share)	$ 33.03
Weighted average exercise price, options exercised (in dollars per share)	$ 21.51
Weighted average exercise price, options forfeited (in dollars per share)	$ 21.00
Weighted average exercise price, options expired (in dollars per share)	$ 23.76
Weighted average exercise price, options outstanding balance end of period (in dollars per share)	$ 23.98
Weighted average exercise price, options exercisable (in dollars per share)	$ 23.66
Weighted average exercise price, options expected to vest (in dollars per share)	$ 24.54
Weighted average remaining contractual term
Weighted average remaining contractual term, options outstanding	5 years 11 months 8 days
Weighted average remaining contractual term, options exercisable	5 years 2 months 1 day
Weighted average remaining contractual term, options expected to vest	7 years 3 months 25 days
Aggregate intrinsic value
Aggregate intrinsic value, options outstanding	70,286
Aggregate intrinsic value, options exercisable	46,537
Aggregate intrinsic value, options expected to vest	22,374
Aggregate intrinsic value of stock options exercised
Aggregate intrinsic value of stock options exercised	5,446	1,064
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	10 years
A portion of stock options effective 2007
Employee stock-based awards
Award vesting period	10 years
Contractual term of awards	12 years
Certain options as a percentage of total outstanding options	9.60%
Certain options beginning in 2011
Employee stock-based awards
Award vesting period	3 years
Contractual term of awards	10 years
Certain options as a percentage of total outstanding options	19.20%
Employee Stock Purchase Plan
Employee Stock Purchase Plan
Employee stock purchase plan, number of offering periods	2
Employee stock purchase plan, duration of offering periods	6 months
Employee stock purchase plan, maximum employee subscription rate percent	15.00%
Percentage of market price for the purchase of shares	95.00%
Employee stock purchase plan, shares issued in period	0	0
Remaining number of shares available for grant	279,226
Restricted Stock and Restricted Stock Units
Dividends accrued
Accrued cash dividends	1,790
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Non-vested at the beginning of the period (in shares)	1,303,664
Granted (in shares)	546,711
Vested (in shares)	(296,846)
Forfeited (in shares)	(19,303)
Non-vested at the end of the period (in shares)	1,534,226
Weighted average grant date fair value
Weighted average grant date fair value, non-vested, beginning of period (in dollars per share)	$ 29.89
Weighted average grant date fair value, granted (in dollars per share)	$ 35.88
Weighted average grant date fair value, vested (in dollars per share)	$ 29.00
Weighted average grant date fair value, forfeited (in dollars per share)	$ 27.21
Weighted average grant date fair value, non-vested, end of period (in dollars per share)	$ 32.23
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
Performance units
Dividends accrued
Accrued cash dividends	573
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Non-vested at the beginning of the period (in shares)	231,646
Granted (in shares)	176,635
Vested (in shares)	(30,803)
Forfeited (in shares)	(2,820)
Non-vested at the end of the period (in shares)	374,658
Weighted average grant date fair value
Weighted average grant date fair value, non-vested, beginning of period (in dollars per share)	$ 29.12
Weighted average grant date fair value, granted (in dollars per share)	$ 38.76
Weighted average grant date fair value, vested (in dollars per share)	$ 29.48
Weighted average grant date fair value, forfeited (in dollars per share)	$ 28.96
Weighted average grant date fair value, non-vested, end of period (in dollars per share)	$ 33.64
Total fair value of shares or units vested	908
Performance units disclosure
Period of anniversary from the date of grant	1 year
Qualifying age for grant of performance units	55 years
Qualifying service period	10 years
Percentage of achievement of the predefined revenue and ROIC targets	100.00%
Performance units | Revenue growth and return on invested capital
Performance units disclosure
Performance period	1 year
Performance units | Market condition associated with shareholder return of common stock
Employee stock-based awards
Award vesting period	3 years
Performance units disclosure
Performance period	3 years
Performance units | Minimum | Revenue growth and return on invested capital
Employee stock-based awards
Award vesting period	1 year
Performance units disclosure
Percentage payout rate	0.00%
Performance units | Minimum | Market condition associated with shareholder return of common stock
Performance units disclosure
Percentage payout rate	0.00%
Performance units | Maximum | Revenue growth and return on invested capital
Employee stock-based awards
Award vesting period	3 years
Performance units disclosure
Percentage payout rate	150.00%
Performance units | Maximum | Market condition associated with shareholder return of common stock
Performance units disclosure
Percentage payout rate	200.00%
Original PU 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)	236,093
Granted (in shares)	202,333
Vested (in shares)	(31,361)
Forfeited (in shares)	(2,820)
Non-vested at the end of the period (in shares)	404,245
PUs Adjustment
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Non-vested at the beginning of the period (in shares)	(4,447)
Granted (in shares)	(25,698)
Vested (in shares)	558
Non-vested at the end of the period (in shares)	(29,587)
Restricted Stock Units
Weighted average grant date fair value
Total fair value of shares or units vested	$ 8,607	$ 3,979
Restricted Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options
Vested (in shares)	0	0