CONSOLIDATED STATEMENTS OF NET INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Income Statement [Abstract]
Service revenues, net	$ 273,219	$ 232,571	$ 817,696	$ 727,889
Product sales and other, net	50,468	48,248	176,726	169,601
Revenues, net	323,687	280,819	994,422	897,490
Cost of services	118,073	111,515	363,284	355,945
Cost of product sales and other	28,526	25,001	100,943	86,521
Cost of revenues	146,599	136,516	464,227	442,466
Gross profit	177,088	144,303	530,195	455,024
Marketing expenses	30,310	30,078	158,707	157,791
Selling, general and administrative expenses	55,400	47,433	153,671	143,152
Operating income	91,378	66,792	217,817	154,081
Interest expense	26,993	28,329	82,227	86,963
Other expense (income), net	125	(146)	278	397
Gain on early extinguishment of debt	0	0	(1,554)	0
Income before income taxes	64,260	38,609	136,866	66,721
Provision for income taxes	19,593	3,989	36,457	12,420
Net income	44,667	34,620	100,409	54,301
Net loss attributable to the noncontrolling interest	52	38	135	99
Net income attributable to Weight Watchers International, Inc.	$ 44,719	$ 34,658	$ 100,544	$ 54,400
Earnings Per Share attributable to Weight Watchers International, Inc.
Basic	$ 0.69	$ 0.54	$ 1.57	$ 0.85
Diluted	$ 0.65	$ 0.53	$ 1.48	$ 0.83
Weighted average common shares outstanding
Basic	64,463	63,782	64,237	63,690
Diluted	68,686	65,841	67,939	65,872

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate cost of goods produced and sold and services rendered during the reporting period.