Stock-Based Compensation Plans (Options Plans) (Details) - Stock Options	3 Months Ended	6 Months Ended
	Jun. 30, 2019 $ / shares shares	Jun. 30, 2019 $ / shares shares
Shares
Beginning balance (in shares) | shares	2,317,523	2,064,740
Granted (in shares) | shares	0	390,789
Exercised (in shares) | shares	(139,978)	(260,761)
Canceled (in shares) | shares	(6,702)	(23,925)
Ending balance (in shares) | shares	2,170,843	2,170,843
Options exercisable at end of period (in shares) | shares	1,410,369	1,410,369
Weighted Average Exercise Price
Beginning balance (in USD per share) | $ / shares	$ 124.24	$ 104.66
Granted (in USD per share) | $ / shares	0	217.58
Exercised (in USD per share) | $ / shares	77.04	80.62
Canceled (in USD per share) | $ / shares	187.44	175.95
Ending balance (in USD per share) | $ / shares	127.09	127.09
Options exercisable at end of period (in USD per share) | $ / shares	$ 79.43	$ 79.43