Stock-Based Compensation Plans (Options Plans) (Details) - Stock Options	3 Months Ended
	Mar. 31, 2019 $ / shares shares
Shares
Beginning balance (in shares) | shares	2,064,740
Granted (in shares) | shares	390,789
Exercised (in shares) | shares	(120,783)
Canceled (in shares) | shares	(17,223)
Ending balance (in shares) | shares	2,317,523
Options exercisable at end of period (in shares) | shares	1,549,179
Weighted Average Exercise Price
Beginning balance (in USD per share) | $ / shares	$ 104.66
Granted (in USD per share) | $ / shares	217.58
Exercised (in USD per share) | $ / shares	84.76
Canceled (in USD per share) | $ / shares	171.49
Ending balance (in USD per share) | $ / shares	124.24
Options exercisable at end of period (in USD per share) | $ / shares	$ 79.52