Notes Payable, Long-Term Debt and Other Obligations (Other Schedules) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Interest expense associated with embedded derivatives	$ 25,732	$ 18,529	$ 32,071
Fair Value Of Derivatives [Roll Forward]
Loss (gain) from changes in fair value of embedded derivatives	(31,710)	(24,455)	(19,409)
Unamortized Debt Discount Reconciliation [Roll Forward]
Amortization of beneficial conversion feature	(12,796)	(8,681)	(19,401)
Convertible Debt
Fair Value Of Derivatives [Roll Forward]
Conversion of Variable Interest Senior Convertible Notes		(889)
Unamortized Debt Discount Reconciliation [Roll Forward]
Beginning balance of unamortized discount	218,255	245,465	201,075
Issuance of convertible notes - embedded derivative			82,775
Increase of convertible notes - beneficial conversion feature			24,974
Amortization of embedded derivatives	(25,732)	(18,529)	(32,071)
Amortization of beneficial conversion feature	(12,796)	(8,681)	(19,401)
Ending balance of unamortized discount	179,727	218,255	245,465
Convertible Debt | Embedded Derivatives
Fair Value Of Derivatives [Roll Forward]
Beginning balance of derivative liability fair value	144,042	169,386	112,062
Increase from issuance			82,775
Loss (gain) from changes in fair value of embedded derivatives	(31,710)	(24,455)	(19,409)
Beginning balance of derivative liability fair value	112,332	144,042	169,386
Convertible Debt | 6.75% Variable Interest Senior Convertible Note due 2015
Debt Instrument [Line Items]
Interest expense associated with embedded derivatives	0	0	6,097
Fair Value Of Derivatives [Roll Forward]
Conversion of Variable Interest Senior Convertible Notes		(889)	(2,511)
Loss (gain) from changes in fair value of embedded derivatives	0	5	(3,212)
Unamortized Debt Discount Reconciliation [Roll Forward]
Beginning balance of unamortized discount	0	0	19,312
Conversion of Variable Interest Senior Convertible Notes			(7,898)
Issuance of convertible notes - embedded derivative			0
Increase of convertible notes - beneficial conversion feature			0
Amortization of embedded derivatives	0	0	(6,097)
Amortization of beneficial conversion feature	0	0	(5,317)
Ending balance of unamortized discount	0	0	0
Convertible Debt | 6.75% Variable Interest Senior Convertible Note due 2015 | Embedded Derivatives
Fair Value Of Derivatives [Roll Forward]
Beginning balance of derivative liability fair value	0	884	6,607
Loss (gain) from changes in fair value of embedded derivatives	0	5	(3,212)
Beginning balance of derivative liability fair value	0	0	884
Convertible Debt | 6.75% Variable Interest Senior Convertible Exchange Notes due 2014
Debt Instrument [Line Items]
Interest expense associated with embedded derivatives	0	0	13,570
Fair Value Of Derivatives [Roll Forward]
Conversion of Variable Interest Senior Convertible Notes			(3,531)
Loss (gain) from changes in fair value of embedded derivatives	0	0	(8,990)
Unamortized Debt Discount Reconciliation [Roll Forward]
Beginning balance of unamortized discount	0	0	25,945
Conversion of Variable Interest Senior Convertible Notes			(3,989)
Issuance of convertible notes - embedded derivative			0
Increase of convertible notes - beneficial conversion feature			0
Amortization of embedded derivatives	0	0	(13,570)
Amortization of beneficial conversion feature	0	0	(8,386)
Ending balance of unamortized discount	0	0	0
Convertible Debt | 6.75% Variable Interest Senior Convertible Exchange Notes due 2014 | Embedded Derivatives
Fair Value Of Derivatives [Roll Forward]
Beginning balance of derivative liability fair value	0	0	12,521
Loss (gain) from changes in fair value of embedded derivatives	0	0	(8,990)
Beginning balance of derivative liability fair value	0	0	0
Convertible Debt | 7.5% Variable Interest Senior Convertible Notes due 2019
Debt Instrument [Line Items]
Interest expense associated with embedded derivatives	14,294	8,777	5,553
Fair Value Of Derivatives [Roll Forward]
Loss (gain) from changes in fair value of embedded derivatives	(19,184)	(15,555)	(5,296)
Unamortized Debt Discount Reconciliation [Roll Forward]
Beginning balance of unamortized discount	132,119	146,634	155,818
Issuance of convertible notes - embedded derivative			0
Increase of convertible notes - beneficial conversion feature			0
Amortization of embedded derivatives	(14,294)	(8,777)	(5,553)
Amortization of beneficial conversion feature	(9,345)	(5,738)	(3,631)
Ending balance of unamortized discount	108,480	132,119	146,634
Convertible Debt | 7.5% Variable Interest Senior Convertible Notes due 2019 | Embedded Derivatives
Fair Value Of Derivatives [Roll Forward]
Beginning balance of derivative liability fair value	72,083	87,638	92,934
Loss (gain) from changes in fair value of embedded derivatives	(19,184)	(15,555)	(5,296)
Beginning balance of derivative liability fair value	52,899	72,083	87,638
Convertible Debt | 5.5% Variable Interest Senior Convertible Debentures due 2020
Debt Instrument [Line Items]
Interest expense associated with embedded derivatives	11,438	9,752	6,851
Fair Value Of Derivatives [Roll Forward]
Loss (gain) from changes in fair value of embedded derivatives	(12,526)	(8,905)	(1,911)
Unamortized Debt Discount Reconciliation [Roll Forward]
Beginning balance of unamortized discount	86,136	98,831	0
Issuance of convertible notes - embedded derivative			82,775
Increase of convertible notes - beneficial conversion feature			24,974
Amortization of embedded derivatives	(11,438)	(9,752)	(6,851)
Amortization of beneficial conversion feature	(3,451)	(2,943)	(2,067)
Ending balance of unamortized discount	71,247	86,136	98,831
Convertible Debt | 5.5% Variable Interest Senior Convertible Debentures due 2020 | Embedded Derivatives
Fair Value Of Derivatives [Roll Forward]
Beginning balance of derivative liability fair value	71,959	80,864	0
Increase from issuance			82,775
Loss (gain) from changes in fair value of embedded derivatives	(12,526)	(8,905)	(1,911)
Beginning balance of derivative liability fair value	$ 59,433	$ 71,959	$ 80,864