Leases (Policies)	9 Months Ended
Sep. 27, 2019
Accounting Policies [Abstract]
Leases	The Company leases certain equipment and facilities. The Company recognizes lease expense for these leases on a straight-line basis over the lease term. Many of these leases include both lease (e.g., fixed payments including rent) and non-lease components (e.g., common-area maintenance or other property management costs). The Company accounts for lease and non-lease components separately. Leases with an initial term of 12 months or less are not recognized on the balance sheet. Most leases held by the Company expire between 2019 and 2034. In the U.K., where longer lease terms are more common, the Company has a land lease that extends through 2078. Certain leases include terms such as an option to purchase the property, one or more options to renew, with renewal terms that can extend the lease term from one to 10 years, and options to terminate the leases within one year. The exercise of lease renewal or termination option is at the Company’s sole discretion; therefore, the majority of renewals to extend the lease terms are not included in the Company’s right-of-use assets and operating lease liabilities as they are not reasonably certain of being exercised. The Company regularly evaluates the renewal options and includes the renewal periods in the lease term when they are reasonably certain of being exercised. The depreciable life of right-of-use assets and leasehold improvements is limited to the expected lease terms. Most leases held by the Company do not provide an implicit rate. The Company uses its incremental borrowing rate for the same jurisdiction and term as the associated lease based on the information available at the lease commencement date to determine the present value of the lease payments. The Company used the incremental borrowing rate as of January 1, 2019 for operating leases that commenced prior to that date. The Company has a centrally managed treasury function; therefore, the Company applies a portfolio approach for determining the incremental borrowing rate based on the applicable lease terms and the current economic environment.

Leases (Policies)

9 Months Ended

Sep. 27, 2019

The Company leases certain equipment and facilities. The Company recognizes lease expense for these leases on a straight-line basis over the lease term. Many of these leases include both lease (e.g., fixed payments including rent) and non-lease components (e.g., common-area maintenance or other property management costs). The Company accounts for lease and non-lease components separately. Leases with an initial term of 12 months or less are not recognized on the balance sheet.

Most leases held by the Company expire between 2019 and 2034. In the U.K., where longer lease terms are more common, the Company has a land lease that extends through 2078. Certain leases include terms such as an option to purchase the property, one or more options to renew, with renewal terms that can extend the lease term from one to 10 years, and options to terminate the leases within one year. The exercise of lease renewal or termination option is at the Company’s sole discretion; therefore, the majority of renewals to extend the lease terms are not included in the Company’s right-of-use assets and operating lease liabilities as they are not reasonably certain of being exercised. The Company regularly evaluates the renewal options and includes the renewal periods in the lease term when they are reasonably certain of being exercised. The depreciable life of right-of-use assets and leasehold improvements is limited to the expected lease terms.

Most leases held by the Company do not provide an implicit rate. The Company uses its incremental borrowing rate for the same jurisdiction and term as the associated lease based on the information available at the lease commencement date to determine the present value of the lease payments. The Company used the incremental borrowing rate as of January 1, 2019 for operating leases that commenced prior to that date. The Company has a centrally managed treasury function; therefore, the Company applies a portfolio approach for determining the incremental borrowing rate based on the applicable lease terms and the current economic environment.