Long-term Debt And Finance Leases - Summary of Long-term Debt and Finance Leases (Parenthetical) (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
6% Convertible Notes Due 2023
Debt Instrument [Line Items]
Debt stated interest rate percentage	6.00%	6.00%
Debt, maturity year	2023	2023
10% senior notes due 2019
Debt Instrument [Line Items]
Debt stated interest rate percentage	10.00%	10.00%
Debt, maturity year	2019	2019