Basis of Presentation and Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2015

Allowance for Doubtful Accounts and Sales Returns Roll Forward [Abstract]

Allowance for Doubtful Accounts and Sales Returns Roll Forward

The following is a summary of the activity of the Company's allowance for doubtful accounts and sales returns for the years ended December 31, 2015, 2014 and 2013 (in thousands):

		Balance at						Balance at
		Beginning						End of
		of Period		Additions		Deductions		Period
Allowance for Doubtful Accounts and Sales
	Returns:
	2015	$	7,179	$	6,739	$	(6,422)	$	7,496
	2014	$	7,057	$	7,551	$	(7,429)	$	7,179
	2013	$	8,240	$	4,386	$	(5,569)	$	7,057

Fair Value Disclosures [Abstract]

Fair Value, Assets And Liabilities

The following table represents the Company's assets and liabilities measured at fair value on a recurring basis at December 31, 2015 (in thousands):

					Quoted Prices
					in Active		Significant
					Markets		Other		Significant
			Total at		for Identical		Observable		Unobservable
			December 31,		Assets		Inputs		Inputs
			2015		(Level 1)		(Level 2)		(Level 3)
Assets:
	U.S. Treasury securities		$	627,156	$	-	$	627,156	$	-
	Foreign government securities			15,199		-		15,199		-
	Corporate debt securities			1,324,318		-		1,324,318		-
	Time deposits			74,947		-		74,947		-
	Equity securities			147		-		147		-
	Other cash equivalents			27,000		-		27,000		-
	Waters 401(k) Restoration Plan assets			35,823		-		35,823		-
	Foreign currency exchange contract
		agreements		616		-		616		-
		Total	$	2,105,206	$	-	$	2,105,206	$	-
Liabilities:
	Contingent consideration		$	4,215	$	-	$	-	$	4,215
	Foreign currency exchange contract
		agreements		402		-		402		-
		Total	$	4,617	$	-	$	402	$	4,215

The following table represents the Company's assets and liabilities measured at fair value on a recurring basis at December 31, 2014 (in thousands):

					Quoted Prices
					in Active		Significant
					Markets		Other		Significant
			Total at		for Identical		Observable		Unobservable
			December 31,		Assets		Inputs		Inputs
			2014		(Level 1)		(Level 2)		(Level 3)
Assets:
	U.S. Treasury securities		$	626,772	$	-	$	626,772	$	-
	Foreign government securities			24,998		-		24,998		-
	Corporate debt securities			984,105		-		984,105		-
	Time deposits			64,240		-		64,240		-
	Equity securities			147		-		147		-
	Other cash equivalents			29,000		-		29,000		-
	Waters 401(k) Restoration Plan assets			33,935		-		33,935		-
	Foreign currency exchange contract
		agreements		123		-		123		-
		Total	$	1,763,320	$	-	$	1,763,320	$	-
Liabilities:
	Contingent consideration		$	3,612	$	-	$	-	$	3,612
	Foreign currency exchange contract
		agreements		651		-		651		-
		Total	$	4,263	$	-	$	651	$	3,612

Summary of Derivative Instruments by Risk Exposure [Abstract]

Gains (Losses) on Foreign Exchange Contracts

The following is a summary of the activity in the statements of operations related to the foreign exchange contracts (in thousands):

		Year Ended December 31,
		2015		2014		2013
Realized (losses) gains on closed contracts		$	(2,601)	$	174	$	8,666
Unrealized gains (losses) on open contracts			742		(1,369)		361
	Cumulative net pre-tax (losses) gains	$	(1,859)	$	(1,195)	$	9,027

Fair Value of Forward Foreign Exchange Contracts

The Company's foreign currency exchange contracts included in the consolidated balance sheets are classified as follows (in thousands):

	December 31, 2015		December 31, 2014
Other current assets	$	616	$	123
Other current liabilities	$	402	$	651

Warranty Accrual Roll Forward [Abstract]

Warranty Accrual Roll Forward

The following is a summary of the activity of the Company's accrued warranty liability for the years ended December 31, 2015, 2014 and 2013 (in thousands):

		Balance at						Balance at
		Beginning		Accruals for		Settlements		End of
		of Period		Warranties		Made		Period
Accrued warranty liability:
	2015	$	13,266	$	8,390	$	(8,307)	$	13,349
	2014	$	12,962	$	8,148	$	(7,844)	$	13,266
	2013	$	12,353	$	8,466	$	(7,857)	$	12,962