Stock Plans (Details) - USD ($)		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Employee service share based compensation aggregate disclosures [Abstract]
Share based compensation cost		$ 17,000,000		$ 55,000,000		$ 46,000,000
Total unrecognized compensation cost related to share-based compensation arrangements		$ 29,000,000
Weighted average period of time over which unrecognized compensation cost is to be recognized		1 year 9 months 18 days
The remaining number of RSU's or stock options that may be issued (in shares)		25,000,000
Additional disclosures for all plans for the period [Abstract]
The remaining balance of shares originally authorized for issue under the employee stock purchase plan (in shares)		6,000,000
The percentage of market value at which shares may be issued to participating employees (in hundredths)		90.00%
The discount percentage off the market value for the employee stock purchase plan (in hundredths)		10.00%
Employee stock purchase plan [Abstract]
The remaining balance of shares originally authorized for issue under the employee stock purchase plan (in shares)		6,000,000
The percentage of market value at which shares may be issued to participating employees (in hundredths)		90.00%
The number of shares issued to participants under the plan during the period		1,386,000		821,000		661,000
The weighted average fair value of each purchase right under the employee stock purchase plan (in dollars per share)		$ 34.39		$ 47.60		$ 50.73
The discount percentage off the market value for the employee stock purchase plan (in hundredths)		10.00%
The aggregate cost of the discount from the market value on shares issued to employees at the end of each monthly purchase period	[1]	$ 3.82		$ 5.29		$ 5.64
Stock Compensation Plan - Board of Directors
Employee service share based compensation aggregate disclosures [Abstract]
Non-option equity instruments granted (in shares)		54,000		31,000		28,000
Weighted average price of non-option equity instruments granted		$ 29.60		$ 52.01		$ 53.01
Restricted stock units
Employee service share based compensation aggregate disclosures [Abstract]
Vesting periods for plans		3 years
The remaining number of RSU's or stock options that may be issued (in shares)		19,000,000
Units (000)
Outstanding RSU's - beginning balance (in shares)		1,545,000		1,342,000		1,294,000
Granted (in shares)		1,235,000	[2]	994,000	[3]	782,000	[4]
Vested (in shares)		(715,000)		(744,000)		(670,000)
Surrendered (in shares)		(103,000)		(47,000)		(64,000)
Outstanding RSU's - ending balance (in shares)		1,962,000		1,545,000		1,342,000
Wtd. Average Fair Value (per share)
Weighted average grant date fair value RSU's - beginning balance (in dollars per share)		$ 57.65		$ 52.56		$ 45.32
Weighted average grant date fair value RSU's - granted (in dollars per share)		56.89		57.49		60.80
Weighted average grant date fair value RSU's - vested (in dollars per share)		54.70		42.42		45.11
Weighted average grant date fair value RSU's - surrendered (in dollars per share)		58.04		57.72		47.05
Weighted average grant date fair value RSU's - period end (in dollars per share)		$ 57.81		$ 57.65		$ 52.56
Performance Shares
Units (000)
Granted (in shares)		519,000		387,000		308,000
Minimum | Performance Shares
Employee service share based compensation aggregate disclosures [Abstract]
Percentage of PBRSUs to be granted		0.00%
Maximum | Performance Shares
Employee service share based compensation aggregate disclosures [Abstract]
Percentage of PBRSUs to be granted		200.00%

[1] The weighted-average fair value of each purchase right under the ESPP granted is equal to a ten percent discount from the market value of the Common Stock at the end of each monthly purchase period.

[2] Includes 519 thousand PBRSUs

[3] Includes 387 thousand PBRSUs

[4] Includes 308 thousand PBRSUs