Commitments and Contingencies - Summary of Land Right Leases (Details)	12 Months Ended
	Dec. 31, 2017
Chengdu, China
Commitments And Contingencies [Line Items]
Land right lease term	50 years
Land Right Lease, Expiration Year	2061
Shanghai, China
Commitments And Contingencies [Line Items]
Land right lease term	50 years
Land Right Lease, Expiration Year	2056
Shandong, China
Commitments And Contingencies [Line Items]
Land right lease term	50 years
Land Right Lease, Expiration Year	2058
Shanghai 1, China
Commitments And Contingencies [Line Items]
Land right lease term	50 years
Land Right Lease, Expiration Year	2058
Yangzhou, China
Commitments And Contingencies [Line Items]
Land right lease term	50 years
Land Right Lease, Expiration Year	2065