Revenue (Policies)	3 Months Ended
Mar. 31, 2019
Revenue [Abstract]
Revenue Recognition, Policy	The vast majority of our service and product contracts are short-term in nature. In recognizing revenue for our services and products, we determine the transaction price of purchase orders or contracts with our customers, which may consist of fixed and variable consideration. Determining the transaction price may require significant judgment, which includes identifying performance obligations in the contract, determining whether promised services can be distinguished in the context of the contract, and estimating the amount of variable consideration to include in the transaction price. We also assess our customer’s ability and intention to pay, which is based on a variety of factors, including our customer’s historical payment experience and financial condition. Payment terms and conditions vary by contract type, although terms generally include a requirement of payment within 20 to 60 days. Other judgments involved in recognizing revenue include an assessment of progress towards completion of performance obligations for certain long-term contracts, which involve estimating total costs to determine our progress towards contract completion and calculating the corresponding amount of revenue to recognize.

Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction.

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84158767&loc=d3e18780-107790

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=84158767&loc=d3e18726-107790

Reference 3: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84158767&loc=d3e18823-107790

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