SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property & Equipment, Patent Costs and Intangibles (Details)			3 Months Ended		12 Months Ended
	Dec. 15, 2017 USD ($)	Aug. 01, 2017 USD ($)	Mar. 31, 2018 USD ($) item	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Apr. 25, 2017 USD ($)
Property, plant and equipment
Property, plant and equipment, gross			$ 145,691,000			$ 118,072,000
Less-Accumulated depreciation			(42,243,000)			(38,086,000)
Property, plant and equipment, net			103,448,000			79,986,000
Assets under construction			50,900,000
Impairment of long-lived assets			$ 0			0
Software Capitalization Policy
Software development stages | item			3
Patent Costs and Intangible Assets
Finite-lived intangible assets			$ 23,660,000			23,660,000
Less: Accumulated amortization			(2,102,000)			(1,500,000)
Total			21,558,000		$ 21,558,000	22,160,000
Amortization expense over remaining useful life
2018					1,805,000
2019					2,407,000
2020					2,407,000
2021					2,373,000
2022					2,370,000
Thereafter					10,196,000
Total			21,558,000		21,558,000	22,160,000
Accrued liabilities			56,716,000			49,126,000
Amortization of intangible assets			612,000	$ 50,000
Impairment losses			0
Sampleminded Inc
Patent Costs and Intangible Assets
Total			900,000			900,000
Amortization expense over remaining useful life
Total			900,000			900,000
Amortization of intangible assets			36,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		$ 1,000,000
Goodwill							$ 2,000,000
Licensed intellectual property and patents
Patent Costs and Intangible Assets
Total					$ 20,675,000
Estimated useful life					10 years 2 months 12 days
Amortization expense over remaining useful life
Total					$ 20,675,000
Amortization of intangible assets			300,000	$ 50,000
Developed Technology
Patent Costs and Intangible Assets
Total					$ 883,000
Estimated useful life					7 years 3 months 18 days
Amortization expense over remaining useful life
Total					$ 883,000
Developed Technology | Sampleminded Inc
Property, plant and equipment
Estimated Useful Life		8 years
Amortization expense over remaining useful life
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		$ 900,000
Customer Relationships | Sampleminded Inc
Property, plant and equipment
Estimated Useful Life		3 years
Amortization expense over remaining useful life
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		$ 100,000
Noncompete Agreements | Sampleminded Inc
Property, plant and equipment
Estimated Useful Life		5 years
Amortization expense over remaining useful life
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		$ 32,000
Armune | Licensed intellectual property and patents
Patent Costs and Intangible Assets
Total			12,000,000			12,200,000
Amortization expense over remaining useful life
Total			12,000,000			12,200,000
Amortization of intangible assets			40,000
Land
Property, plant and equipment
Property, plant and equipment, gross			4,466,000			4,466,000
Leasehold and building improvements
Property, plant and equipment
Property, plant and equipment, gross			17,452,000			17,629,000
Assets under construction			32,900,000
Expected cost to complete project			239,200,000
Land improvements
Property, plant and equipment
Property, plant and equipment, gross			$ 1,419,000			$ 1,419,000
Estimated Useful Life			15 years			15 years
Buildings
Property, plant and equipment
Property, plant and equipment, gross			$ 7,928,000			$ 7,928,000
Estimated Useful Life			30 years			30 years
Computer equipment and computer software
Property, plant and equipment
Property, plant and equipment, gross			$ 32,716,000			$ 30,148,000
Estimated Useful Life			3 years			3 years
Assets under construction			$ 1,700,000
Expected cost to complete project			1,600,000
Laboratory equipment
Property, plant and equipment
Property, plant and equipment, gross			26,234,000			$ 23,296,000
Assets under construction			16,300,000
Expected cost to complete project			$ 16,000,000
Laboratory equipment | Minimum
Property, plant and equipment
Estimated Useful Life			3 years			3 years
Laboratory equipment | Maximum
Property, plant and equipment
Estimated Useful Life			5 years			5 years
Furniture and fixtures
Property, plant and equipment
Property, plant and equipment, gross			$ 4,554,000			$ 4,531,000
Estimated Useful Life			3 years			3 years
Assets under construction
Property, plant and equipment
Property, plant and equipment, gross			$ 50,922,000			$ 28,655,000
Royalty Buy-Out Agreement | MDx
Amortization expense over remaining useful life
One-time fee for a royalty-free, fully-paid, perpetual and assignable license to patents								$ 8,000,000
Payment for the assignment of certain other patent rights which were not covered by the original agreement								7,000,000
Total payment under second amendment to license agreement								15,000,000
Current liabilities related to the second amendment to the license agreement								$ 6,600,000
Royalty Buy-Out Agreement | MDx | Licensed intellectual property and patents
Patent Costs and Intangible Assets
Total			8,700,000			9,000,000
Amortization expense over remaining useful life
Total			$ 8,700,000			$ 9,000,000
Asset Purchase Agreement | Armune | Licensed intellectual property and patents
Amortization expense over remaining useful life
Purchases of intangible assets	$ 12,000,000
Contingent payment obligations	17,500,000
Intangible asset acquired	$ 12,200,000