Amount of long-term debt, excluding current maturities and including debt issuance cost.

No definition available.

Name:	ctrp_LongTermDebtExcludingCurrentMaturitiesAndIncludingDebtIssuanceCost
Namespace Prefix:	ctrp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the number of affiliates.

+ References

No definition available.

+ Details

Name:	ctrp_NumberOfAffiliates
Namespace Prefix:	ctrp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of shares agreed to be sold by the counterparty on exercise of Purchased Call option.

+ References

No definition available.

+ Details

Name:	ctrp_NumberOfSharesAgreedToBeSoldOnExerciseOfPurchasedCallOptions
Namespace Prefix:	ctrp_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The proceeds from termination of purchased call options.

+ References

No definition available.

+ Details

Name:	ctrp_ProceedsFromTerminationOfPurchasedCallOptions
Namespace Prefix:	ctrp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The value of the financial instrument(s) that the original debt is being converted into in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586

+ Details

Name:	us-gaap_DebtConversionConvertedInstrumentAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

+ Details

Name:	us-gaap_DebtConversionConvertedInstrumentSharesIssued1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031898-161870

+ Details

Name:	us-gaap_DebtInstrumentConvertibleConversionPrice1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(5))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentConvertibleConversionRatio1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

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

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

Name:	us-gaap_LongTermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebtNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from issuance of rights to purchase common shares at predetermined price (usually issued together with corporate debt).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfWarrants
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Per share or per unit amount of equity securities issued.

+ References

No definition available.

+ Details

Name:	us-gaap_SharesIssuedPricePerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=ctrp_BorrowingsCollateralizedByStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ctrp_ConvertibleDebt2018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ctrp_AdsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CallOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PositionAxis=us-gaap_LongMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_WarrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ctrp_ConvertibleDebt2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ctrp_ConvertibleDebt2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ctrp_ConvertibleDebt2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ctrp_PricelineConvertibleNotesOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ctrp_PricelineConvertibleNotesTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ctrp_PricelineAndHillhouseConvertibleNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ctrp_PricelineConvertibleNotesThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ctrp_PricelineConvertibleNotesFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ctrp_ConvertibleDebt2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ctrp_PricelineGroupAndHillhouseNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

LONG-TERM DEBT (Details)					1 Months Ended	12 Months Ended
LONG-TERM DEBT (Details)	Sep. 19, 2016 USD ($) $ / shares	Jun. 18, 2015 USD ($) $ / shares shares	Oct. 17, 2013 USD ($) $ / shares shares	Sep. 24, 2012 USD ($) $ / shares shares	Jun. 30, 2017 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2017 CNY (¥) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2016 CNY (¥) shares	Dec. 31, 2015 CNY (¥)	Dec. 31, 2017 CNY (¥)	Sep. 12, 2016 USD ($) $ / shares	Dec. 10, 2015 USD ($) item $ / shares	May 26, 2015 USD ($) $ / shares	Aug. 07, 2014 USD ($) $ / shares
LONG-TERM DEBT
Long-term loan \| ¥									¥ 2,550,000,000		¥ 8,807,156,482
Less: Debt issuance costs \| ¥									(184,276,447)		(81,746,715)
Total						$ 4,491,070,926			34,650,673,553		29,220,254,767
Fair value of long-term debt, based on Level 2 inputs						29,300,000,000
Proceeds from sale of warrants \| ¥										¥ 523,404,000
Notes for early conversion						368,221,572	¥ 2,395,760,015		2,604,871,611	¥ 118,973,721
Proceeds from the termination of 2012 and 2013 Purchased Call Option						100,000,000	¥ 650,000,000	$ 12,000,000
Borrowings collateralized by stock at a wholly-owned subsidiary
LONG-TERM DEBT
Aggregate principal amount						$ 1,400,000,000					¥ 8,800,000,000
Borrowings collateralized by stock at a wholly-owned subsidiary \| Minimum
LONG-TERM DEBT
Interest rate (as a percent)						1.90%					1.90%
Borrowings collateralized by stock at a wholly-owned subsidiary \| Maximum
LONG-TERM DEBT
Interest rate (as a percent)						7.00%					7.00%
2018 Notes
LONG-TERM DEBT
Long-term loan \| ¥									5,554,400,000
Interest rate (as a percent)			1.25%
Aggregate principal amount			$ 800,000,000		$ 327,000,000
Debt issuance costs			$ 19,600,000
Notes for early conversion						$ 352,000,000
2018 Notes \| ADS
LONG-TERM DEBT
Initial conversion rate			0.0127568
Initial conversion price (in dollars per share) \| $ / shares			$ 78.39		$ 39.19
Number of shares agreed to be sold by the counterparty on exercise of Purchased Call option \| shares					8,300,000
Number of shares issued upon exchange of notes \| shares						10.8	10.8
2018 Notes \| ADS \| Purchased Call Option
LONG-TERM DEBT
Share price agreed to be sold by the counterparty on exercise of Purchased call option \| $ / shares			$ 78.39
2018 Notes \| ADS \| Purchased Call Option \| Long \| Maximum
LONG-TERM DEBT
Number of shares agreed to be sold by the counterparty on exercise of Purchased Call option \| shares			10,200,000
2018 Notes \| ADS \| Sold Warrants
LONG-TERM DEBT
Proceeds from sale of warrants			$ 77,200,000
Exercise price of warrants sold (in dollars per share) \| $ / shares			$ 96.27
2018 Notes \| ADS \| Sold Warrants \| Maximum
LONG-TERM DEBT
Number of shares that can be purchased from warrants sold \| shares			10,200,000
2020 Notes
LONG-TERM DEBT
Long-term loan \| ¥									4,860,100,000
Interest rate (as a percent)		1.00%
Initial conversion rate		0.0091942
2020 Notes \| ADS
LONG-TERM DEBT
Initial conversion price (in dollars per share) \| $ / shares		$ 108.76
2025 Notes
LONG-TERM DEBT
Long-term loan \| ¥									2,777,200,000		¥ 2,602,520,000
Interest rate (as a percent)		1.99%
Aggregate principal amount		$ 400,000,000
Debt issuance costs		$ 6,800,000
Initial conversion rate		0.0093555
2025 Notes \| ADS
LONG-TERM DEBT
Initial conversion price (in dollars per share) \| $ / shares		$ 106.89
2022 Notes
LONG-TERM DEBT
Long-term loan \| ¥									6,769,425,000		6,343,642,500
Interest rate (as a percent)	1.25%
Initial conversion rate	0.0152688
2022 Notes \| ADS
LONG-TERM DEBT
Initial conversion price (in dollars per share) \| $ / shares	$ 65.49
2019 Priceline Note
LONG-TERM DEBT
Long-term loan \| ¥									3,471,500,000		3,253,150,000
Interest rate (as a percent)															1.00%
Aggregate principal amount															$ 500,000,000
2019 Priceline Note \| ADS
LONG-TERM DEBT
Initial conversion price (in dollars per share) \| $ / shares															$ 81.36
2020 Priceline Notes
LONG-TERM DEBT
Long-term loan \| ¥									1,735,750,000		1,626,575,000
Interest rate (as a percent)														1.00%
Aggregate principal amount		$ 700,000,000												$ 250,000,000
Debt issuance costs		$ 11,300,000
2020 Priceline Notes \| ADS
LONG-TERM DEBT
Initial conversion price (in dollars per share) \| $ / shares														$ 104.27
Number of shares that can be purchased from warrants sold \| shares		6,400,000
2020 Priceline Notes \| ADS \| Sold Warrants
LONG-TERM DEBT
Proceeds from sale of warrants		$ 84,400,000
Number of shares that can be purchased from warrants sold \| shares		6,400,000
2025 Priceline and Hillhouse Notes
LONG-TERM DEBT
Long-term loan \| ¥									6,943,000,000		6,506,300,000
Interest rate (as a percent)													2.00%
2025 Priceline and Hillhouse Notes \| ADS
LONG-TERM DEBT
Initial conversion price (in dollars per share) \| $ / shares													$ 68.46
2022 Priceline Notes
LONG-TERM DEBT
Long-term loan \| ¥									¥ 173,575,000		¥ 162,657,500
Interest rate (as a percent)												1.25%
2022 Priceline Notes \| ADS
LONG-TERM DEBT
Initial conversion price (in dollars per share) \| $ / shares												$ 65.49
2022 Priceline Notes
LONG-TERM DEBT
Aggregate principal amount	$ 975,000,000											$ 25,000,000
Debt issuance costs	$ 19,000,000
2017 Notes
LONG-TERM DEBT
Interest rate (as a percent)				0.50%
Aggregate principal amount				$ 180,000,000
Debt issuance costs				$ 5,400,000
Notes for early conversion								$ 26,000,000
2017 Notes \| ADS
LONG-TERM DEBT
Initial conversion rate				0.0517116
Initial conversion price (in dollars per share) \| $ / shares				$ 19.34
Number of shares issued upon exchange of notes \| shares								2.6	2.6
2017 Notes \| ADS \| Purchased Call Option
LONG-TERM DEBT
Share price agreed to be sold by the counterparty on exercise of Purchased call option \| $ / shares				$ 19.34
2017 Notes \| ADS \| Purchased Call Option \| Long \| Maximum
LONG-TERM DEBT
Number of shares agreed to be sold by the counterparty on exercise of Purchased Call option \| shares				9,300,000
2017 Notes \| ADS \| Sold Warrants
LONG-TERM DEBT
Proceeds from sale of warrants				$ 26,600,000
Number of shares that can be purchased from warrants sold \| shares				9,300,000
Exercise price of warrants sold (in dollars per share) \| $ / shares				$ 26.37
Priceline and Hillhouse Notes
LONG-TERM DEBT
Aggregate principal amount													$ 1,000,000,000
Number of affiliates \| item													2