Fair Value Measurement of Assets and Liabilities (Narrative) (Details) - USD ($) $ in Thousands	Jun. 30, 2019		Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	$ 1,756,766		$ 917,796
Short-term Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	1,374,577		441,485
Auction Rate Securities [Member] | Direct Investment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	0		0
Non-financial assets	0		0
Non-financial liabilities	0		$ 0
2028 Convertible Senior Notes [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net carrying amount	$ 627,654
Central Bank of Brazil Mandatory Guarantee [Member] | Short-term Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Percent of electronic currency deposited	100.00%		80.00%
Estimated Fair Value	$ 339,299	[1]	$ 284,317

[1] Brazilian government bonds measured at fair value with impact on the consolidated statement of income for the application of the fair value option. (See Note 2 – Fair value option applied to certain financial instruments)