Stock-Based Compensation (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) plan $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares	Jan. 18, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share-based compensation plans covering employees, officers and directors | plan	4
Expiration period of stock options (in years)	10 years
Previous discretionary goal	50.00%
Stock Option, Intrinsic Value
Weighted average grant date fair value of options (in dollars per share) | $ / shares	$ 4.73	$ 5.89	$ 4.37
Employee Benefit Plan
Maximum 401(K) plan contribution by employer as a percent of employee's salary	3.50%
Aggregate employer 401(K) plan contribution during the period | $	$ 1,300	$ 1,200	$ 1,100
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance	3,000
Number of shares available for future issuance	2,900
Nonvested Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Value
Number of shares purchased	100
Employee Stock | Employee
Nonvested Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Value
Discount related to the Employee Stock Purchase Plan	90.00%
Employee Stock | Director
Nonvested Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Value
Discount related to the Employee Stock Purchase Plan	95.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	2 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Stock Options
Fair value assumptions of stock options using Black-Scholes option pricing model
Risk-free interest rate, minimum	0.93%	1.02%	1.30%
Risk-free interest rate, maximum	1.27%	1.38%	1.40%
Dividend yield	5.50%	5.00%	5.00%
Volatility factors of the expected market price for our common stock, minimum rate	19.10%	19.00%	17.80%
Volatility factors of the expected market price for our common stock, maximum rate	20.60%	20.00%	18.00%
Weighted average expected life of options, maximum (in years)	4 years	4 years	4 years 2 months 1 day
Stock Option, Shares
Outstanding at the beginning of the period (in shares)	3,052
Granted (in shares)	1,165
Options exercised (in shares)	409
Options forfeited (in shares)	2
Options expired (in shares)	1
Outstanding at the end of the period (in shares)	3,805	3,052
Exercisable at the end of the period (in shares)	2,629
Stock Option, Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 52.62
Options granted (in dollars per share) | $ / shares	62.82
Options exercised (in dollars per share) | $ / shares	49.77
Options forfeited (in dollars per share) | $ / shares	58.84
Options expired (in dollars per share) | $ / shares	46.62
Outstanding at the end of the period (in dollars per share) | $ / shares	56.05	$ 52.62
Exercisable at the end of the period (in dollars per share) | $ / shares	$ 53.23
Stock Option, Weighted Average Remaining Contractual Life (years)
Outstanding at the end of the period (in years)	7 years 2 months 12 days
Exercisable at the end of the period (in years)	6 years 4 months 24 days
Stock Option, Intrinsic Value
Outstanding at the end of the period | $	$ 30,379
Exercisable at the end of the period | $	27,075
Unrecognized compensation cost related to nonvested awards | $	$ 2,200
Weighted average period over which cost is recognized (in years)	1 year 2 months 5 days
Proceeds from options exercised | $	$ 20,400	$ 6,400	$ 26,200
Intrinsic value for options exercised | $	8,000	4,700	19,300
Stock Options | General and administrative expenses
Stock Option, Intrinsic Value
Compensation cost | $	6,200	4,200	4,700
Restricted Stock or Restricted Stock Units
Stock Option, Intrinsic Value
Unrecognized compensation cost related to nonvested awards | $	$ 6,900
Weighted average period over which cost is recognized (in years)	1 year 4 months 24 days
Nonvested Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Value
Intrinsic value for options vested during period | $	$ 13,900	18,300	17,700
Restricted Stock or Restricted Stock Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	2 years
Restricted Stock or Restricted Stock Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	5 years
Restricted Stock or Restricted Stock Units | General and administrative expenses
Stock Option, Intrinsic Value
Compensation cost | $	$ 14,700	$ 15,200	$ 16,200
Restricted Stock
Nonvested Restricted Stock and Restricted Stock Units, Shares
Nonvested at the beginning of the period (in shares)	0
Granted (in shares)	0
Vested (in shares)	0
Forfeited (in shares)	0
Nonvested at the end of the period (in shares)	0	0
Nonvested Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Value
Nonvested at the beginning of the period (in dollars per share) | $ / shares	$ 57.65
Granted (in dollars per share) | $ / shares	55.25
Vested (in dollars per share) | $ / shares	56.21
Forfeited (in dollars per share) | $ / shares	58.18
Nonvested at the end of the period (in dollars per share) | $ / shares	$ 57.29	$ 57.65
Restricted Stock Units
Nonvested Restricted Stock and Restricted Stock Units, Shares
Nonvested at the beginning of the period (in shares)	0
Granted (in shares)	0
Vested (in shares)	0
Forfeited (in shares)	0
Nonvested at the end of the period (in shares)	0	0
Nonvested Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Value
Nonvested at the beginning of the period (in dollars per share) | $ / shares	$ 58.02
Granted (in dollars per share) | $ / shares	57.06
Vested (in dollars per share) | $ / shares	56.19
Forfeited (in dollars per share) | $ / shares	0.00
Nonvested at the end of the period (in dollars per share) | $ / shares	$ 58.70	$ 58.02
2012 Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance	10,500
Number of shares available for future issuance	6,500
Executive Deferred Stock Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share-based compensation plans for executive officers | plan	1
Number of shares authorized for issuance	600
Number of shares available for future issuance	600
Nonemployee Directors' Deferred Stock Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share-based compensation plans for directors | plan	1
Number of shares authorized for issuance	600
Number of shares available for future issuance	500
Subsequent Event | 2017 LTIP | Performance Based RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocation of awards				60.00%
Subsequent Event | 2017 LTIP | Time Based RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocation of awards				40.00%