Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Schedule Of Significant Accounting Policies [Line Items]
Revenue of all other clients individually			Less than 5%
Largest amount of tax benefit			Greater than 50%
Provision for interest or penalties related to uncertain tax positions	$ 0		$ 0
Florida Cancer Specialists [Member]
Schedule Of Significant Accounting Policies [Line Items]
Number of FSC's practice locations from which testing services will be performed			72
Sales [Member] | Florida Cancer Specialists [Member]
Schedule Of Significant Accounting Policies [Line Items]
Percentage of revenue derived from	7.90%	16.50%	10.50%	15.80%
Sales [Member] | Florida [Member]
Schedule Of Significant Accounting Policies [Line Items]
Percentage of revenue derived from	22.00%	29.50%	25.60%	30.90%