Share-based Compensation (Summary of Information Concerning Stock Options Outstanding Including the Related Transactions under the Stock Option Plans) (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($) $ / shares shares
Share-based Compensation [Abstract]
Balance, number of shares (in shares) | shares	13,172
Granted, number of shares (in shares) | shares	10,653
Exercised, number of shares (in shares) | shares	(681)
Forfeited and expired, number of shares (in shares) | shares	(69)
Balance, number of shares (in shares) | shares	23,075
Options Expected to Vest, number of shares (in shares) | shares	22,612
Options Exercisable, number of shares (in shares) | shares	9,273
Balance, weighted-average exercise price (in dollars per share) | $ / shares	$ 21.94
Granted, weighted-average exercise price (in dollars per share) | $ / shares	19.65
Exercised, weighted-average exercise price (in dollars per share) | $ / shares	17.99
Forfeited and expired, weighted-average exercise price (in dollars per share) | $ / shares	20.41
Balance, weighted-average exercise price (in dollars per share) | $ / shares	21.00
Options Expected to Vest, weighted-average exercise price (in dollars per share) | $ / shares	21.02
Options Exercisable, weighted-average exercise price (in dollars per share) | $ / shares	$ 19.34
Options Outstanding, weighted-average remaining contractual term in years (Year)	7 years 1 month 13 days
Options Expected to Vest, weighted-average remaining contractual term in years (Year)	7 years 21 days
Options Exercisable, weighted-average remaining contractual term in years (Year)	3 years 7 months 2 days
Options Outstanding, aggregate intrinsic value | $	$ 128,954
Options Expected to Vest, aggregate intrinsic value | $	126,208
Options Exercisable, aggregate intrinsic value | $	$ 62,467