LEASES (Policies)	3 Months Ended
Mar. 31, 2019
Leases [Abstract]
Lessee, Leases	The Company has operating leases for office space, data centers and one land lease for Booking.com's headquarters (see Note 13). The Company has no finance leases as of March 31, 2019. For office space, data centers and land, the Company has elected to combine the fixed payments to lease the asset and any fixed non-lease payments (such as maintenance or utility charges) when calculating the lease asset and lease liability. The Company recognizes lease expense on a straight-line basis over the lease term. Certain of our lease agreements include rent payments which are adjusted periodically for inflation. Any change in payments due to changes in inflation rates are recognized as variable lease expense as they are incurred. Variable lease expense also includes costs for property taxes, insurance and services provided by the lessor which are charged based on usage or performance. Most leases have one or more options to renew, with renewal terms that can initially extend the lease term for various periods up to 9 years. The exercise of renewal options for office space and data centers is at the Company’s discretion and are included if they are reasonably certain to be exercised. The land lease for Booking.com's headquarters has an initial term which expires in 2065, at which time the lease payments will be adjusted based on the value of the land on the reassessment date. The Company considered the initial term of the land lease to be its expected period of use. As of March 31, 2019, the Company’s weighted-average remaining lease term for all leases was approximately 8.2 years. When the rate implicit in the lease is not readily determinable, the Company uses its incremental borrowing rate as its discount rate to determine the present value of its lease payments. The incremental borrowing rates approximate the rate the Company would pay to borrow in the currency of the lease payments on a collateralized basis for the weighted-average life of the lease. As of March 31, 2019, the Company’s weighted-average discount rate was approximately 2.0%.

The Company has operating leases for office space, data centers and one land lease for Booking.com's headquarters (see Note 13). The Company has no finance leases as of March 31, 2019. For office space, data centers and land, the Company has elected to combine the fixed payments to lease the asset and any fixed non-lease payments (such as maintenance or utility charges) when calculating the lease asset and lease liability.

The Company recognizes lease expense on a straight-line basis over the lease term. Certain of our lease agreements include rent payments which are adjusted periodically for inflation. Any change in payments due to changes in inflation rates are recognized as variable lease expense as they are incurred. Variable lease expense also includes costs for property taxes, insurance and services provided by the lessor which are charged based on usage or performance.

Most leases have one or more options to renew, with renewal terms that can initially extend the lease term for various periods up to 9 years. The exercise of renewal options for office space and data centers is at the Company’s discretion and are included if they are reasonably certain to be exercised. The land lease for Booking.com's headquarters has an initial term which expires in 2065, at which time the lease payments will be adjusted based on the value of the land on the reassessment date. The Company considered the initial term of the land lease to be its expected period of use. As of March 31, 2019, the Company’s weighted-average remaining lease term for all leases was approximately 8.2 years.

When the rate implicit in the lease is not readily determinable, the Company uses its incremental borrowing rate as its discount rate to determine the present value of its lease payments. The incremental borrowing rates approximate the rate the Company would pay to borrow in the currency of the lease payments on a collateralized basis for the weighted-average life of the lease. As of March 31, 2019, the Company’s weighted-average discount rate was approximately 2.0%.