Stock-based Compensation Expense and Share Repurchase - Stock Options Outstanding and Exercisable (Details) shares in Thousands	3 Months Ended
	Jun. 30, 2019 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price range, options outstanding (in shares) | shares	8,194
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	7 years 1 month 20 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 126.39
Exercise price range, options exercisable (in shares) | shares	4,543
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 106.24
$29.07–$40.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	29.07
Exercise price, high end of range (in dollars per share)	$ 40
Exercise price range, options outstanding (in shares) | shares	204
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	1 year 8 months 1 day
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 36.87
Exercise price range, options exercisable (in shares) | shares	204
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 36.87
$40.01–$60.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	40.01
Exercise price, high end of range (in dollars per share)	$ 60
Exercise price range, options outstanding (in shares) | shares	401
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	2 years 11 months 15 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 49.90
Exercise price range, options exercisable (in shares) | shares	401
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 49.90
$60.01–$80.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	60.01
Exercise price, high end of range (in dollars per share)	$ 80
Exercise price range, options outstanding (in shares) | shares	305
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	4 years 10 months 13 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 73.09
Exercise price range, options exercisable (in shares) | shares	298
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 73.02
$80.01–$100.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	80.01
Exercise price, high end of range (in dollars per share)	$ 100
Exercise price range, options outstanding (in shares) | shares	2,367
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	6 years 7 months 24 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 89.22
Exercise price range, options exercisable (in shares) | shares	1,459
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 89.74
$100.01–$120.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	100.01
Exercise price, high end of range (in dollars per share)	$ 120
Exercise price range, options outstanding (in shares) | shares	616
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	5 years 7 months 6 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 109.31
Exercise price range, options exercisable (in shares) | shares	610
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 109.26
$120.01–$140.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	120.01
Exercise price, high end of range (in dollars per share)	$ 140.00
Exercise price range, options outstanding (in shares) | shares	746
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	6 years 1 month 20 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 130.24
Exercise price range, options exercisable (in shares) | shares	685
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 130.31
$140.01–$160.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	140.01
Exercise price, high end of range (in dollars per share)	$ 160.00
Exercise price range, options outstanding (in shares) | shares	1,245
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	8 years 7 months 2 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 155.51
Exercise price range, options exercisable (in shares) | shares	407
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 155.39
$160.01–$180.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	160.01
Exercise price, high end of range (in dollars per share)	$ 180.00
Exercise price range, options outstanding (in shares) | shares	523
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	8 years 1 month 20 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 163.28
Exercise price range, options exercisable (in shares) | shares	236
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 163.59
$180.01–$189.38
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise price, low end of range (in dollars per share)	180.01
Exercise price, high end of range (in dollars per share)	$ 189.38
Exercise price range, options outstanding (in shares) | shares	1,787
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	9 years 4 months 17 days
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 185.32
Exercise price range, options exercisable (in shares) | shares	243
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 184.18