Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28555-108399

Name:	us-gaap_DeferredFinanceCostsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

DEBT - ADS Lending Arrangement (Details) - ADS Lending Arrangement $ / shares in Units, ¥ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017 CNY (¥) shares	Dec. 31, 2020 shares	Dec. 31, 2019 shares	Dec. 31, 2018 shares	Dec. 31, 2017 USD ($) $ / shares
Debt Instrument [Line Items]
Number of Loaned ADS lent	2,606,278
ADS par value per share \| $ / shares					$ 0.0004
ADS outstanding		10,425,112	10,425,112	10,425,112
Debt issuance costs	¥ 26				$ 4