v3.8.0.1

Quarterly Financial Information (unaudited) - Summary of Quarterly Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Jan. 01, 2017	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Dec. 31, 2017	Jan. 01, 2017	Jan. 03, 2016
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 778	$ 714	$ 662	$ 598	$ 619	$ 607	$ 600	$ 572	$ 2,752	$ 2,398	$ 2,220
Gross profit	542	482	434	368	419	426	424	397	1,826	1,666	1,549
Consolidated net income	58	152	120	348	108	117	116	88	678	428	458
Net income attributable to Illumina stockholders	$ 68	$ 163	$ 128	$ 367	$ 124	$ 129	$ 120	$ 90	$ 726	$ 463	$ 462
Earnings per share attributable to Illumina stockholders:
Earnings per share attributable to Illumina stockholders, basic (in dollars per share)	$ 0.47	$ 1.12	$ 0.87	$ 2.50	$ 0.84	$ 0.88	$ 0.83	$ 0.61	$ 4.96	$ 3.09	$ 3.19
Earnings per share attributable to Illumina stockholders, diluted (in dollars per share)	$ 0.46	$ 1.11	$ 0.87	$ 2.48	$ 0.84	$ 0.87	$ 0.82	$ 0.60	$ 4.92	$ 3.07	$ 3.10

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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