Additional Cash Flow Information (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 3,593,412	$ 3,109,322	$ 2,893,885	$ 2,650,134
Cash, cash equivalents and restricted cash per statement of cash flows	3,601,964	3,120,681	2,901,532	2,658,253
Prepaid expenses and other current assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and cash equivalents	8,552	8,004	6,250	4,910
Other assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and cash equivalents	$ 0	$ 3,355	$ 1,397	$ 3,209