CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Accounts receivable, unbilled services with related parties	$ 1.3	$ 1.0
Pre-funded study costs with related parties		1.0
Advanced billings with related parties	$ 0.3	$ 1.7
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock shares authorized	5,000,000	5,000,000
Preferred stock shares issued	0	0
Preferred stock shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock shares authorized	250,000,000	250,000,000
Common stock shares issued	35,504,675	35,466,510
Common stock shares outstanding	35,504,675	35,466,510
Treasury stock shares	200,000	200,000