Summary of Significant Accounting Policies - Supplemental Cash Flows (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Accounting Policies [Abstract]
Operating cash flows used in operating leases	$ 338,059
Operating cash flows used in financing leases (interest)	21,031
Financing cash flows used in financing leases	58,033
Operating lease modifications and reassessments	108,023
New operating leases (including acquisitions)	170,464
New financing leases, modifications and reassessments	$ 32,742