Stock-Based Compensation, Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Shares [Roll Forward]
Exercised (in shares)	(500,000)	(1,200,000)	(1,100,000)
Stock Options [Member]
Number of Shares [Roll Forward]
Outstanding at beginning of year (in shares)	3,694,400
Granted (in shares)	920,100
Exercised (in shares)	(489,600)
Forfeited/cancelled/expired (in shares)	(707,700)
Outstanding at end of year (in shares)	3,417,200	3,694,400
Exercisable at end of year (in shares)	1,064,800
Weighted-Average Exercise Price [Roll Forward]
Outstanding at beginning of year (in dollars per share)	$ 54.17
Granted (in dollars per share)	71.19
Exercised (in dollars per share)	37.25
Forfeited/cancelled/expired (in dollars per share)	75.23
Outstanding at end of year (in dollars per share)	56.81	$ 54.17
Exercisable at end of year (in dollars per share)	$ 41.44
Remaining Contractual Term and Aggregate Intrinsic Value [Abstract]
Outstanding options, weighted-average remaining contractual term	3 years 11 months 19 days
Outstanding options, aggregate intrinsic value	$ 39,519
Exercisable options, weighted-average remaining contractual term	3 years 5 months 1 day
Exercisable options, aggregate intrinsic value	$ 23,746
Service-Based Options [Member]
Number of Shares [Roll Forward]
Outstanding at beginning of year (in shares)	1,392,900
Granted (in shares)	0
Exercised (in shares)	(337,700)
Forfeited/cancelled/expired (in shares)	(8,800)
Outstanding at end of year (in shares)	1,046,400	1,392,900
Exercisable at end of year (in shares)	648,600
Weighted-Average Exercise Price [Roll Forward]
Outstanding at beginning of year (in dollars per share)	$ 39.76
Granted (in dollars per share)	0
Exercised (in dollars per share)	37.40
Forfeited/cancelled/expired (in dollars per share)	39.45
Outstanding at end of year (in dollars per share)	40.53	$ 39.76
Exercisable at end of year (in dollars per share)	$ 43.72
Remaining Contractual Term and Aggregate Intrinsic Value [Abstract]
Outstanding options, weighted-average remaining contractual term	3 years 6 months 11 days
Outstanding options, aggregate intrinsic value	$ 24,330
Exercisable options, weighted-average remaining contractual term	3 years 29 days
Exercisable options, aggregate intrinsic value	$ 19,984
Performance-Based Options [Member]
Number of Shares [Roll Forward]
Outstanding at beginning of year (in shares)	2,301,500
Granted (in shares)	920,100
Exercised (in shares)	(151,900)
Forfeited/cancelled/expired (in shares)	(698,900)
Outstanding at end of year (in shares)	2,370,800	2,301,500
Exercisable at end of year (in shares)	416,200
Weighted-Average Exercise Price [Roll Forward]
Outstanding at beginning of year (in dollars per share)	$ 62.89
Granted (in dollars per share)	71.19
Exercised (in dollars per share)	36.91
Forfeited/cancelled/expired (in dollars per share)	75.68
Outstanding at end of year (in dollars per share)	64.00	$ 62.89
Exercisable at end of year (in dollars per share)	$ 37.88
Remaining Contractual Term and Aggregate Intrinsic Value [Abstract]
Outstanding options, weighted-average remaining contractual term	4 years 1 month 28 days
Outstanding options, aggregate intrinsic value	$ 15,190
Exercisable options, weighted-average remaining contractual term	3 years 11 months 12 days
Exercisable options, aggregate intrinsic value	$ 9,762