Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net income	$ 660.0	$ 735.9	$ 588.8
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and loss on disposal of property, plant, and equipment, net	86.2	73.9	65.1
Amortization of intangible assets	12.9	18.2	24.4
Loss on investment, accretion of discounts, and amortization of premiums on investments, net	21.2	35.9	26.4
Deferred income taxes	62.9	18.7	4.6
Income tax benefits from employee stock plans	0.0	29.8	21.5
Share-based compensation expense	209.1	177.6	167.9
Changes in operating assets and liabilities, net of effects of acquisition:
Accounts receivable	(81.7)	(35.9)	(79.2)
Inventory	(115.5)	(46.7)	(10.7)
Prepaids and other assets	(28.5)	(28.7)	(10.5)
Accounts payable	14.0	15.9	(11.3)
Accrued compensation and employee benefits	31.2	18.7	21.5
Deferred revenue	52.8	19.9	8.2
Other liabilities	219.3	53.8	(10.5)
Net cash provided by operating activities (1)	1,143.9	1,087.0	806.2
Investing activities:
Purchase of investments	(1,995.0)	(2,585.5)	(1,827.4)
Proceeds from sales of investments	1,861.3	389.9	233.1
Proceeds from maturities of investments	703.1	970.1	825.8
Purchase of property, plant and equipment, and intellectual property	(190.7)	(53.9)	(81.0)
Net cash provided by (used in) investing activities	378.7	(1,279.4)	(849.5)
Financing activities:
Proceeds from issuance of common stock relating to employee stock plans	415.5	580.9	361.1
Taxes paid related to net share settlement of equity awards	(56.6)	(24.0)	(11.0)
Repurchase and retirement of common stock	(2,274.0)	(42.5)	(183.7)
Other financing activities	2.0	0.0	(7.3)
Net cash provided by (used in) financing activities (1)	(1,913.1)	514.4	159.1
Effect of exchange rate changes on cash and cash equivalents	2.1	0.0	(1.5)
Net increase (decrease) in cash and cash equivalents	(388.4)	322.0	114.3
Cash and cash equivalents, beginning of year	1,036.6	714.6	600.3
Cash and cash equivalents, end of year	$ 648.2	1,036.6	714.6
ASU No. 2016-09
Changes in operating assets and liabilities, net of effects of acquisition:
Net cash provided by operating activities (1)		44.1	34.3
Financing activities:
Net cash provided by (used in) financing activities (1)		$ (44.1)	$ (34.3)

Depreciation and Gain (Loss) on Disposition of Property Plant Equipment

No definition available.

Name:	isrg_DepreciationandGainLossonDispositionofPropertyPlantEquipment
Namespace Prefix:	isrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The sum of the periodic adjustments of the differences between securities' face values and purchase prices that are charged against earnings. This is called accretion if the security was purchased at a discount and amortization if it was purchased at premium. As a noncash item, this element is an adjustment to net income when calculating cash provided by or used in operations using the indirect method.