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Summary of Significant Accounting Policies - Additional Information - Concentration of Credit Risk (Detail) | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Services Revenue [Member] | Customer Concentration Risk [Member] | Minimum [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage | 10.00% | 10.00% | 10.00%
Services Revenue [Member] | Customer Concentration Risk [Member] | Medicare [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage | 44.00% | 50.00% | 51.00%
Product Revenue [Member] | Customer Concentration Risk [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage | 26.00% |  |
Product Revenue [Member] | Customer Concentration Risk [Member] | Minimum [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage | 10.00% |  |
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Minimum [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage | 10.00% | 10.00% |
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Medicare [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage | 27.00% | 35.00% |
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Aetna [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage | 6.00% | 21.00% |

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