Stock-Based Incentive Plans (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	6 Months Ended		1 Months Ended		6 Months Ended		1 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Feb. 28, 2011 1994 Plan	Feb. 28, 2010 1994 Plan	Jun. 30, 2011 1994 Plan	Feb. 02, 2010 1994 Plan	Feb. 28, 2011 1995 Plan	Feb. 15, 2011 1995 Plan
Stock-Based Incentive Plans
Number of Stock Incentive Plans	1
Number of Stock Option Plans Superseded	2
Black-Scholes option pricing model assumptions for options granted
Number of Options Granted (in shares)	1,392		1,362	148			30
Risk Free Interest Rate (as a percent)			2.62%	2.93%			2.92%
Dividend Yield (as a percent)			1.75%	1.62%			1.76%
Expected Life (in years)			6.2	6.5			6.6
Volatility (as a percent)			39.00%	36.00%			38.00%
Exercise price for options granted, low end of range (in dollars per share)			$ 29.66
Exercise price for options granted, high end of range (in dollars per share)			$ 32.63
Exercise Price (in dollars per share)						$ 24.75		$ 29.58
Weighted Average Fair Value (in dollars per share)			$ 10.33	$ 8.46			$ 10.49
Non-Qualified Stock Options activity
Outstanding at the beginning of the period (in shares)	1,124
Granted (in shares)	1,392		1,362	148			30
Excercised (in shares)	(7)
Forfeited (in shares)	(16)
Outstanding at the end of the period (in shares)	2,493
Outstanding and expected to vest at the end of the period (in shares)	2,436
Exercisable at the end of the period (in shares)	1,083
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 34.19
Granted (in dollars per share)	$ 29.66
Exercised (in dollars per share)	$ 23.74
Forfeited (in dollars per share)	$ 35.69
Outstanding at the end of the period (in dollars per share)	$ 31.68
Outstanding and expected to vest at end of the period (in dollars per share)	$ 31.74
Exercisable at end of the period (in dollars per share)	$ 35.04
Weighted-Average Remaining Contractual Life
Outstanding at the end of the period (in years)	4.6
Outstanding and expected to vest at end of the period (in years)	4.6
Exercisable at end of the period (in years)	2.2
Aggregate Intrinsic Value
Outstanding at the end of the period (in dollars)	$ 1,873,000
Outstanding and expected to vest at end of the period (in dollars)	1,817,000
Exercisable at end of the period (in dollars)	773,000
Closing price of share (in dollars per share)	$ 29.87
Total intrinsic value of options exercised (in dollars)	40,000	300,000
Number of shares, unvested options
Unvested at the beginning of the period (in shares)	180
Granted (in shares)	1,392
Vested (in shares)	(161)
Forfeited (in shares)	(1)
Unvested at the end of the period (in shares)	1,410
Weighted-Average Grant-Date Fair Value, unvested stock options
Unvested at the beginning of the period (in dollars per share)	$ 7.85
Granted (in dollars per share)	$ 10.33
Vested (in dollars per share)	$ 9.88
Forfeited (in dollars per share)	$ 6.55
Unvested at the end of the period (in dollars per share)	$ 10.07
Unrecognized compensation cost
Unrecognized compensation costs related to unvested share-based compensation arrangements (in dollars)					$ 9,900,000
Weighted-average period for recognition of unrecognized stock-based compensation expense (in years)					3.5