Loss Per Share - Anti-dilutive Securities (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average securities not included in computation of diluted shares outstanding (in shares)	16,284	10,702	35,770
Shares issuable for the contingent consideration
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average securities not included in computation of diluted shares outstanding (in shares)	7,421	8,553	4,640
Shares issuable upon conversion of PDH Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average securities not included in computation of diluted shares outstanding (in shares)	5,967	0	8,318
Shares issuable upon conversion of Series A Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average securities not included in computation of diluted shares outstanding (in shares)	2,000	2,000	2,000
Shares issuable upon vesting of RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average securities not included in computation of diluted shares outstanding (in shares)	842	147	74
Shares issuable upon vesting and exercise of stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average securities not included in computation of diluted shares outstanding (in shares)	51	0	55
Shares issuable under the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average securities not included in computation of diluted shares outstanding (in shares)	3	2	1
Shares issuable upon conversion of Series B Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average securities not included in computation of diluted shares outstanding (in shares)	0	0	19,443
Shares contingently issuable to Founder Entities as stock dividend to Series A Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average securities not included in computation of diluted shares outstanding (in shares)	0	0	1,239