Commitments and Contingencies - Additional Information (Detail)			3 Months Ended		6 Months Ended
	Jul. 01, 2016 USD ($)	Apr. 25, 2016 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2016 SEK	Jun. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)
Minimum [Member]
Loss Contingencies [Line Items]
Special fine by disciplinary committee					$ 6,000	SEK 50,000
Maximum [Member]
Loss Contingencies [Line Items]
Special fine by disciplinary committee					$ 12,000,000	SEK 100,000,000
Oberland Complaint [Member]
Loss Contingencies [Line Items]
Damages sought		$ 1,400,000
CareDx [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Damages sought	$ 1,300,000
Unpaid Royalties [Member]
Loss Contingencies [Line Items]
Settlement and mutual release agreement, counterparty name					Roche	Roche
Settlement and mutual release agreement, date					September 2014	September 2014
Past due royalties								$ 2,827,220
Maximum number of days from end of calendar quarter for royalty payment					45 days	45 days
Settlement and mutual release agreement, terms of agreement					In September 2014, the Company entered into a settlement and mutual release agreement with Roche whereby: (i)?for the period beginning July?1, 2011 through June?30, 2014, the Company agreed to pay the amount of $2,827,220 in settlement of past royalties due; (ii)?for the period beginning July?1, 2014 through September?30, 2014, the Company agreed to pay royalties based on the same combination services percentage used to determine the past royalties due; (iii)?for the period beginning October?1, 2014 through September?30, 2017, Roche and the Company agreed to a downward adjustment of the combination services percentage used to determine the portion of the AlloMap testing revenue that is royalty bearing under the terms of the license; (iv)?the Company agreed to report and pay quarterly royalties within 45 days of the end of each calendar quarter; (v)?Roche agreed that, subject to the Company?s timely payment of all applicable royalties through such date, no further royalties will be payable by the Company for periods after September?30, 2017.	In September 2014, the Company entered into a settlement and mutual release agreement with Roche whereby: (i)?for the period beginning July?1, 2011 through June?30, 2014, the Company agreed to pay the amount of $2,827,220 in settlement of past royalties due; (ii)?for the period beginning July?1, 2014 through September?30, 2014, the Company agreed to pay royalties based on the same combination services percentage used to determine the past royalties due; (iii)?for the period beginning October?1, 2014 through September?30, 2017, Roche and the Company agreed to a downward adjustment of the combination services percentage used to determine the portion of the AlloMap testing revenue that is royalty bearing under the terms of the license; (iv)?the Company agreed to report and pay quarterly royalties within 45 days of the end of each calendar quarter; (v)?Roche agreed that, subject to the Company?s timely payment of all applicable royalties through such date, no further royalties will be payable by the Company for periods after September?30, 2017.
Royalty expenses			$ 300,000	$ 300,000	$ 500,000		$ 500,000