Organization and Summary of Significant Accounting Policies Principles of Consolidation (Details) (USD $)	0 Months Ended	3 Months Ended
	Feb. 18, 2015	Mar. 31, 2015 country subsidiary Test	Mar. 31, 2014	Dec. 31, 2014
Principles of Consolidation
Number of wholly-owned subsidiaries		2
Revenue Recognition
Minimum Number of Tests by Exclusive Distribution Agreements		1
Minimum Number of Countries Covered for Exclusive Distribution Agreements		90
Accrued refunds		$ 1,100,000	$ 944,000
Contracts Revenue		0	0
Allowance for Doubtful Accounts
Allowance for Doubtful Accounts Receivable, Write-offs		1,000,000	1,500,000
Bad debt expense		1,000,000	1,500,000
Investments in Privately Held Companies
Initial public offering of its common stock and converted to common stock (in shares)	2,207,793
Available-for-sale marketable security	37,000,000
Property and equipment | Minimum
Property and Equipment and Internal-Use Software
Estimated useful lives of the assets		3 years
Property and equipment | Maximum
Property and Equipment and Internal-Use Software
Estimated useful lives of the assets		7 years
Private company 2
Investments in Privately Held Companies
Carrying value of investments in privately held companies				$ 13,900,000
Genomic Health International Holdings, LLC
Principles of Consolidation
Number of wholly-owned subsidiaries		10