Stock-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) plan $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($)
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
Stock Option, Intrinsic Value
Proceeds from stock option exercises | $	$ 36,179,000	$ 8,762,000	$ 16,287,000
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 | $	$ 1,500,000	$ 1,500,000	1,400,000
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance	2,900,000
Number of shares authorized for issuance	3,000,000.0
Nonvested Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Value
Number of shares purchased	100,000
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%
Stock Options
Stock Option, Shares
Outstanding at the beginning of the period (in shares)	4,783,000
Granted (in shares)	0
Options exercised (in shares)	(700,000)
Options forfeited (in shares)	(6,000)
Options exercised (in shares)	0
Outstanding at the end of the period (in shares)	4,077,000	4,783,000
Exercisable at the end of the period (in shares)	4,014,000
Stock Option, Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 59.20
Options granted (in dollars per share) | $ / shares	0
Options exercised (in dollars per share) | $ / shares	0
Options exercised (in dollars per share) | $ / shares	51.68
Options forfeited (in dollars per share) | $ / shares	60.50
Outstanding at the end of the period (in dollars per share) | $ / shares	60.49	$ 59.20
Exercisable at the end of the period (in dollars per share) | $ / shares	$ 60.49
Stock Option, Weighted Average Remaining Contractual Life (years)
Outstanding at the end of the period (in years)	5 years 8 months 12 days
Exercisable at the end of the period (in years)	5 years 8 months 12 days
Stock Option, Intrinsic Value
Outstanding at the end of the period | $	$ 7,379,000
Exercisable at the end of the period | $	7,415,000
Proceeds from stock option exercises | $	36,100,000	$ 8,800,000	16,300,000
Intrinsic value for options exercised | $	12,300,000	3,100,000	7,000,000.0
Deferred income tax expense (benefit) | $	0
Stock Options | General, administrative and professional fees
Stock Option, Intrinsic Value
Compensation cost | $	300,000	2,600,000	4,800,000
Restricted Stock or Restricted Stock Units
Stock Option, Intrinsic Value
Unrecognized compensation cost related to nonvested awards | $	$ 15,100,000
Weighted average period over which cost is recognized (in years)	1 year 7 months 28 days
Nonvested Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Value
Intrinsic value for options vested during period | $	$ 31,600,000	15,500,000	16,600,000
Restricted Stock or Restricted Stock Units | General, administrative and professional fees
Stock Option, Intrinsic Value
Compensation cost | $	$ 33,600,000	$ 27,300,000	$ 21,700,000
Restricted Stock
Nonvested Restricted Stock and Restricted Stock Units, Shares
Nonvested at the beginning of the period (in shares)	276,000
Granted (in shares)	143,000
Vested (in shares)	(149,000)
Forfeited (in shares)	(22,000)
Nonvested at the end of the period (in shares)	248,000	276,000
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	$ 53.64
Granted (in dollars per share) | $ / shares	62.69
Vested (in dollars per share) | $ / shares	54.20
Forfeited (in dollars per share) | $ / shares	57.24
Nonvested at the end of the period (in dollars per share) | $ / shares	$ 58.21	$ 53.64
Restricted Stock Units
Nonvested Restricted Stock and Restricted Stock Units, Shares
Nonvested at the beginning of the period (in shares)	628,000
Granted (in shares)	304,000
Vested (in shares)	(371,000)
Forfeited (in shares)	(22,000)
Nonvested at the end of the period (in shares)	539,000	628,000
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	$ 57.70
Granted (in dollars per share) | $ / shares	59.85
Vested (in dollars per share) | $ / shares	60.73
Forfeited (in dollars per share) | $ / shares	53.69
Nonvested at the end of the period (in dollars per share) | $ / shares	$ 56.99	$ 57.70
Minimum | Restricted Stock or Restricted Stock Units
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
Maximum | Restricted Stock or Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	5 years
2006 Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance	0
2012 Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance	3,000,000.0
Number of shares authorized for issuance	10,500,000
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 available for future issuance	600,000
Number of shares authorized for issuance	600,000
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 available for future issuance	400,000
Number of shares authorized for issuance	600,000