Notes Payable, Long-Term Debt and Other Obligations (Conversion Rates on Convertible Debt) (Details) - Variable Interest Senior Convertible Debt - 5.5% Variable Interest Senior Convertible Notes due 2020	12 Months Ended
	Dec. 31, 2020 $ / shares	Dec. 31, 2019 $ / shares
Debt Instrument [Line Items]
Conversion price (in dollars per share)	$ 0	$ 20.27
Conversion ratio	0	49.3363