Share-Based Compensation (Details) - Parent Issuer UHS - Options - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Number of Options
Outstanding at the beginning of the period (in shares)	37,673
Granted (in shares)	500
Exercised (in shares)	(390)
Forfeited or expired (in shares)	(198)
Outstanding at the end of the period (in shares)	37,585	37,673
Exercisable at the end of the period (in shares)	20,303
Remaining authorized options available for issue	5,466
Weighted average exercise price
Outstanding at the beginning of the period (in dollars per share)	$ 0.79
Granted (in dollars per share)	1.87
Exercised (in dollars per share)	0.71
Forfeited or expired (in dollars per share)	0.77
Outstanding at the end of the period (in dollars per share)	0.80	$ 0.79
Exercisable at the end of the period (in dollars per share)	$ 0.75
Aggregate intrinsic value
Outstanding	$ 40,204	$ 40,875
Exercisable	22,639
Exercised	$ 452
Weighted average remaining contractual term
Outstanding	6 years 7 months 6 days	6 years 9 months 18 days
Exercisable	6 years 7 months 6 days