v3.8.0.1

Share-based Compensation Expense | 12 Months Ended
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Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |
Share-based Compensation Expense | Share-based Compensation Expense Share-based compensation expense for all stock awards consists of the following (in millions):
| Years Ended
| December 31, 2017 |  | January 1, 2017 |  | January 3, 2016
Cost of product revenue | $ | 12 |  |  | $ | 9 |  |  | $ | 10 |
Cost of service and other revenue | 2 |  |  | 2 |  |  | 2 |
Research and development | 51 |  |  | 42 |  |  | 42 |
Selling, general and administrative | 99 |  |  | 76 |  |  | 79 |
Share-based compensation expense before taxes | 164 |  |  | 129 |  |  | 133 |
Related income tax benefits | (48 | ) |  | (41 | ) |  | (39 | )
Share-based compensation expense, net of taxes | $ | 116 |  |  | $ | 88 |  |  | $ | 94 |
The assumptions used for the specified reporting periods and the resulting estimates of weighted-average fair value per share for stock purchased under the ESPP are as follows:
| Years Ended
| December 31, 2017 |  | January 1, 2017 |  | January 3, 2016
Risk-free interest rate | 0.50% - 1.22% |  |  | 0.40% - 0.50% |  |  | 0.07% - 0.33% |
Expected volatility | 29% - 44% |  |  | 40% - 44% |  |  | 29% - 38% |
Expected term | 0.5 - 1.0 year |  |  | 0.5 - 1.0 year |  |  | 0.5 - 1.0 year |
Expected dividends | 0 | % |  | 0 | % |  | 0 | %
Weighted-average grant-date fair value per share | $ | 46.81 |  |  | $ | 48.29 |  |  | $ | 53.92 |
As of December 31, 2017, approximately $394 million of total unrecognized compensation cost related to restricted stock and ESPP shares issued to date are expected to be recognized over a weighted-average period of approximately 2.7 years.

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- Definition The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -URI http://asc.fasb.org/topic&trid=2228938 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 50 -URI http://asc.fasb.org/subtopic&trid=2208855 + Details
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