Stock Options, Stock Purchase Plan and Warrants - Additional Information (Detail) - USD ($)						12 Months Ended
	Mar. 16, 2014	Mar. 12, 2014	Feb. 07, 2014	Jan. 09, 2012	Jan. 01, 2007	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 30, 2015	May. 03, 2010
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Amended Plan expiration date						Oct. 15, 2025
Common stock reserved and available for issuance under the Amended Plan						12,500,000
Stock option outstanding						5,326,505	4,012,096	5,725,298	5,777,212
Stock option to purchase						1,819,000	760,500	416,000
Shares were available for future option and stock awards under the Amended Plan						4,081,940
Aggregate intrinsic value of all stock options outstanding and expected to vest						$ 25,500,000
Aggregate intrinsic value of currently exercisable stock options						$ 16,000,000
Common stock closing price						$ 7.87
Total number of in the money options outstanding and exercisable										2,600,000
Total intrinsic value of options exercised						$ 2,470,000	$ 8,882,000	$ 1,200,000
Total cash proceeds received from the exercise of stock options						714,000	1,807,000	372,000
Total fair value of options granted						3,347,000	1,139,000	493,000
Total fair value of option shares vested						871,000	$ 540,000	$ 349,000
Unrecognized stock-based compensation cost						$ 4,861,000
Unrecognized cost is expected to be recognized over a weighted-average period						1 year 4 months 24 days
Shares issued under ESPP						73,958	90,285	76,595
Albitar warrant period									5 years
Number of remaining warrants un-vested						120,000
Proceeds from stock options exercised			$ 62,500
Common stock warrants issued to the Consultant (Steven Jones)											450,000
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 1.48					$ 1.50
Albitar Warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock compensation expense						$ 422,000	$ 49,000	$ 231,000
Options expiry period				Jan. 09, 2017
Albitar Warrants [Member] | Vesting at Commercial Launch [Member] | Plasma Prostate Cancer Test Licensed From Health Discovery Corp HDC [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants granted				80,000
Albitar Warrants [Member] | Vesting at Commercial Launch [Member] | Colon Cancer Test Licensed From HDC [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants granted				40,000
Albitar Warrants [Member] | Vesting at Commercial Launch [Member] | Pancreatic Cancer Test Licensed From HDC [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants granted				40,000
Albitar Warrants [Member] | Vesting at Successful Consummation Of Sublicensing Agreement[Member] | Cytogenetics Automated Image Analysis Technology Licenses From HDC [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants granted				20,000
Albitar Warrants [Member] | Vesting at Successful Consummation Of Sublicensing Agreement[Member] | Cytometry Automated Image Analysis Technology Licenses From HDC [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants granted				20,000
Warrant [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock compensation expense						$ 0	$ 51,000	$ 263,000
Warrants granted				200,000		0	0	0
Weighted average exercise price, granted				$ 1.43		$ 0	$ 0	$ 0
Deemed value per share				$ 4.00
Value of Albitar Warrants						$ 920,000
Number of remaining warrants un-vested						120,000	120,000
Warrants exercised		375,000	83,333			0	458,333	0
Exercise price of warrants		$ 1.05	$ 0.75
Proceeds from stock options exercised		$ 393,750
Warrants issued and expired	250,000					0	250,000	0
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Limited payroll deductions a discount					5.00%
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock compensation expense						$ 2,889,000	$ 511,000	$ 666,000
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options expiry period						5 years
Stock option term						3 years
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options expiry period						10 years
Stock option term						4 years
Chief Executive Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option to purchase						800,000