Equity-Method Investments - Additional Information (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2010 USD ($) investment shares	Mar. 31, 2019 USD ($)
Schedule of Equity Method Investments [Line Items]
Impairment of investments in joint venture		$ 0	$ 0	$ 6,496
Proceeds from sale of investments in partially owned entities		14,250	0	0
Equity method investment, realized gain (loss) on disposal		4,297	0	0
Equity method investment		$ 0	$ 14,541
China JV
Schedule of Equity Method Investments [Line Items]
Cash investments in joint venture					$ 1,300	$ 46,200
Number of newly formed investments | investment						2
Equity interest						49.00%
Equity interest by CMHI						51.00%
Impairment of investments in joint venture				$ 6,500
Proceeds from sale of investments in partially owned entities	$ 15,000
Equity method investment, realized gain (loss) on disposal	4,300
China JV | Reclassification out of Accumulated Other Comprehensive Income | Foreign currency translation adjustment
Schedule of Equity Method Investments [Line Items]
Equity method investment, realized gain (loss) on disposal	$ 2,600
Joint Venture
Schedule of Equity Method Investments [Line Items]
Equity method investment							$ 2,000
Series B Preferred Shares | CMHI
Schedule of Equity Method Investments [Line Items]
Number of shares sold (in shares) | shares						50,000