Long-term Debt (Maturities of Long-Term Debt) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Future minimum repayments of long-term debt
Within one year	$ 140
2-3 years	1,324,321
4-5 years	1,825,317
Over 5 years	2,650,000
Total minimum payments	$ 5,799,778	$ 5,799,879