REVENUE

On January 1, 2018, the Company adopted ASC 606 "Revenue from Contracts with Customers" and all the related amendments using the modified retrospective method, whereby the adoption did not impact any prior periods. The effect of adopting the new standard did not require any cumulative effect adjustment to retained earnings as of January 1, 2018. There was no impact to our consolidated statements of operations, balance sheet, or statement of cash flows as of and for the period ended March 31, 2018.

The Company disaggregates revenue from contracts with customers by product, service, timing of revenue recognition, and geography. A summary by the Company’s reportable segments follows:



For the three month ended March 31, 2019	U.S. Operations		Swiss Operations		Western European Operations		Chinese Operations		Other Operations		Total
Product Revenue	$	174,256	$	26,665	$	116,555	$	111,416	$	95,455	$	524,347
Service Revenue:
Point in time	49,651		4,951		33,939		7,704		24,018		120,263
Over time	10,743		1,961		15,412		2,603		4,123		34,842
Total	$	234,650	$	33,577	$	165,906	$	121,723	$	123,596	$	679,452



For the three month ended March 31, 2018	U.S. Operations		Swiss Operations		Western European Operations		Chinese Operations		Other Operations		Total
Product Revenue	$	172,501	$	25,565	$	116,932	$	104,292	$	91,656	$	510,946
Service Revenue:
Point in time	47,619		4,830		34,590		7,127		24,237		118,403
Over time	9,625		2,071		13,850		2,511		3,415		31,472
Total	$	229,745	$	32,466	$	165,372	$	113,930	$	119,308	$	660,821

In certain circumstances, our reporting units sell directly into other geographies. A breakdown of net sales to external customers by geographic customer destination for the three months ended March 31 follows:



	2019		2018
Americas	$	258,631	$	252,279
Europe	209,555		205,840
Asia / Rest of World	211,266		202,702
Total	$	679,452	$	660,821

The Company's global revenue mix by product category is laboratory (53% of sales), industrial (40% of sales) and retail (7% of sales). The Company's product revenue by reportable segment is proportionately similar to the Company's global mix except the Company's Swiss Operations is largely comprised of laboratory products, while the Company's Chinese Operations has a slightly higher percentage of industrial products. A breakdown of the Company’s sales by product category for the three months ended March 31 follows:



	2019		2018
Laboratory	$	359,732	$	345,159
Industrial	271,320		262,656
Retail	48,400		53,006
Total	$	679,452	$	660,821

The payment terms in the Company’s contracts with customers do not exceed one year and therefore contracts do not contain a significant financing component. In most cases, after appropriate credit evaluations, payments are due in arrears and are recognized as receivables. Unbilled revenue is recorded when performance obligations have been satisfied, but not yet billed to the customer. Unbilled revenue as of March 31, 2019 and December 31, 2018 was $16.2 million and $12.4 million respectively, and is included within accounts receivable. Deferred revenue and customer prepayments are recorded when cash payments are received or due in advance of the performance obligation being satisfied. Deferred revenue primarily includes prepaid service contracts, as well as deferred installation.

Changes in the components of deferred revenue and customer prepayments during the periods ended March 31, 2019 and 2018 are as follows:



	2019			2018
Beginning balances as of December 31	$	105,381		$	107,166
Customer pre-payments/deferred revenue	167,599			151,009
Revenue recognized	(144,303		)	(129,796		)
Foreign currency translation	285			2,325
Ending balance as of March 31	$	128,962		$	130,704

The Company generally expenses sales commissions when incurred because the contract period is one year or less. These costs are recorded within selling, general, and administrative expenses. The Company has not disclosed the value of unsatisfied performance obligations other than customer pre-payments and deferred revenue above as most contracts have an expected length of one year or less and amounts greater than one year are immaterial.