Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Future interest payable - current	[1]	$ 120,258	$ 105,125
Future interest payable - long-term		$ 2,643,307	$ 2,664,211
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		463,728,262	462,355,725
Treasury stock, shares		2,473,243	1,941,749
Future interest payable on senior secured notes
Debt Instrument [Line Items]
Future interest payable - current		$ 102,667	$ 85,303
Future interest payable - long-term		$ 147,550	$ 164,914

[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”) and 9¼% Senior Secured Second Lien Notes due 2022 (the “2022 Senior Secured 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, 2019 include $102.7 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.