Out-License of Marqibo, Zevalin, & Evolema in China Territory - Additional Information (Detail) $ in Thousands, shares in Millions		1 Months Ended	9 Months Ended	12 Months Ended
	Sep. 17, 2014 shares	Sep. 30, 2014 agreement	Sep. 30, 2018 USD ($) shares	Dec. 31, 2017 shares	Dec. 31, 2016 shares	Dec. 31, 2015 USD ($)
Other Commitments [Line Items]
Equity securities			$ 53,928
CASI Out-License [Member]
Other Commitments [Line Items]
Number of agreements | agreement		3
Shares received (shares) | shares	5.4			1.5	4.6
Number of shares held in investment (shares) | shares			11.5
Percentage of ownership			12.36%
Equity securities			$ 53,900
Undiscounted proceeds						$ 9,700