Employee Stock-Based Compensation and Benefit Plans (Narrative) (Details) $ / shares in Units, $ in Thousands			1 Months Ended				12 Months Ended
	Apr. 22, 2019 USD ($)	Aug. 01, 2017 shares	Apr. 30, 2019 shares	Feb. 28, 2019 shares	Mar. 31, 2018 shares	Mar. 31, 2017 $ / shares shares	Dec. 31, 2019 USD ($) plan installment $ / shares shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock-based compensation plans offered | plan							1
Stock-based compensation | $							$ 278,892	$ 203,619	$ 165,120
Deferred tax asset related to stock-based compensation | $							54,400	39,700	46,100
Tax benefit from compensation expense | $							$ 59,500	49,700	72,900
401(k) Benefit Plan [Abstract]
Maximum annual contribution per employee (as a percent)							90.00%
Contribution per dollar of employee contribution							50.00%
Matching percent							3.00%
Defined Contribution Plan, Cost | $							$ 14,400	13,000	13,700
Market and service condition stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested stock unit awards granted to senior level employees (shares) | shares						275,148
Performance period						3 years
Total return to shareholders as percentile of peer group, minimum						41.00%
Total return to shareholders as percentile of peer group, maximum						80.00%
Maximum share cap based on target shareholder return (percent)						100.00%
Minimum share cap based on target shareholder return (percent)						200.00%
Minimum peer group percentile to achieve target share cap						80.00%
Period to determine actual stock grant following end of interim measurement period						60 days
Market performance stock units and company performance stock units, change in control modification
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation | $	$ 0
Maximum percentage of market and service condition stock units that will ultimately vest with change of control (percent)	2
Non-vested stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation | $							$ 266,500	193,800	149,800
Non-vested stock unit awards granted to senior level employees (shares) | shares							3,444,414
Expected life (in years)						2 years 9 months
Granted (in dollars per share) | $ / shares						$ 104.05	$ 97.98
Share-based compensation award, stock vesting period, monthly installments | installment							12
Fair value of awards released | $							$ 246,700	$ 149,300	150,000
Share-based awards granted and outstanding (in shares) | shares							5,688,534	5,853,501
Total unrecognized compensation cost related to stock-based compensation | $							$ 392,100
Total unrecognized compensation cost recognition period (in years)							1 year 8 months 8 days
Non-vested stock | Annual vesting on each anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage							33.33%
Non-vested stock (Modified)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)						1 year 21 days
Granted (in dollars per share) | $ / shares						$ 99.54
Performance stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period to determine actual stock grant following end of performance period		60 days	60 days	60 days	60 days
Maximum percentage of market and service condition stock units that will ultimately vest		200.00%	200.00%		200.00%
2014 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance under the Plans (shares) | shares							11,894,175
Shares available for grant under the Plan (shares) | shares							6,156,746
2014 Plan | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance under the Plan (shares) | shares							43,400,000
Fungible share factor							2.75
2015 ESPP Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance under the Plan (shares) | shares							16,000,000
Employee Stock Purchase Plan, payment period							6 months
Employee Stock Purchase Plan, maximum number of shares per period that employees can purchase (shares) | shares							12,000
Employee Stock Purchase Plan, lower of purchase price offered on either first or last day of payment period as a percentage of fair market value (percent)							85.00%
Employee Stock Purchase Plan, employee disqualification, ownership percent of outstanding stock							5.00%
Employee Stock Purchase Plan, total shares issued under plan (shares) | shares							2,192,755
Stock-based compensation | $									$ 10,000
Expected life (in years)							6 months	6 months	6 months
2015 ESPP Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Purchase Plan, option to purchase shares through payroll deduction, payroll deduction amount per pay period per employee, as a percentage of base pay							1.00%
2015 ESPP Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Purchase Plan, option to purchase shares through payroll deduction, payroll deduction amount per pay period per employee, as a percentage of base pay							10.00%
Employee Stock Purchase Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation | $							$ 12,400	$ 9,800
Senior Level Employees | Performance stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested stock unit awards granted to senior level employees (shares) | shares		184,322	293,991	93,500	268,729