Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Future interest payable - current	[1]	$ 129,667	$ 105,188
Future interest payable - long-term		$ 2,923,378	$ 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		402,927,941	402,549,346
Treasury stock, shares		787,867	457,041
Future interest payable on senior secured and convertible senior notes
Debt Instrument [Line Items]
Future interest payable - current		$ 100,083	$ 75,347
Future interest payable - long-term		$ 256,140	$ 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, 9¼% Senior Secured Second Lien Notes due 2022 (the “2022 Senior Secured Notes”), 5% Convertible Senior Notes due 2023 (the “2023 Convertible Senior Notes”), and 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 March 31, 2018 include $100.1 million of future interest payable related to these notes that is due within the next twelve months. See January 2018 Note Exchanges below for further discussion.