Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Future interest payable - current	[1]	$ 111,335	$ 105,188
Future interest payable - long-term		$ 2,689,647	$ 2,979,086
Stockholders' equity
Preferred stock, par value		$ 0.001	$ 0.001
Preferred stock, shares authorized		25,000,000	25,000,000
Preferred stock, shares issued		0	0
Preferred stock, shares outstanding		0	0
Common stock, par value		$ 0.001	$ 0.001
Common stock, shares authorized		600,000,000	600,000,000
Common stock, shares issued		458,214,337	402,549,346
Treasury stock, shares		806,318	457,041
Future interest payable on senior secured and convertible senior notes
Debt Instrument [Line Items]
Future interest payable - current		$ 84,932	$ 75,347
Future interest payable - long-term		$ 207,659	$ 241,472

[1] Future interest payable represents most of the interest due over the terms of our 9% Senior Secured Second Lien Notes due 2021 (the “2021 Senior Secured Notes”), 9¼% Senior Secured Second Lien Notes due 2022 (the “2022 Senior Secured Notes”), and to a lesser extent our previously outstanding 3½% Convertible Senior Notes due 2024 (the “2024 Convertible Senior Notes”) and has been accounted for as debt in accordance with FASC 470-60, Troubled Debt Restructuring by Debtors. Our current maturities of long-term debt as of June 30, 2018 include $84.9 million of future interest payable related to the 2021 Senior Secured Notes and 2022 Senior Secured Notes that is due within the next twelve months. See January 2018 Note Exchanges below for further discussion.