Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	JDS Silver [Member]	JDS Silver [Member] Common Stock	JDS Silver [Member] Additional Paid-In Capital
Balances at Dec. 31, 2018	$ 852,512	$ 2,033	$ 3,443,082	$ (2,592,544)	$ (59)
Balances, in shares at Dec. 31, 2018		203,310
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(19,201)			(19,201)
Other comprehensive income (loss)	59				59
Common stock issued under stock-based compensation plans, net (in shares)		1,801
Common stock issued under stock-based compensation plans, net	(1,035)	$ 18	(1,053)
Balances at Mar. 31, 2019	832,335	$ 2,051	3,442,029	(2,611,745)	0
Balances, in shares at Mar. 31, 2019		205,111
Balances at Dec. 31, 2018	852,512	$ 2,033	3,443,082	(2,592,544)	(59)
Balances, in shares at Dec. 31, 2018		203,310
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(70,242)
Other comprehensive income (loss)	1,191
Balances at Sep. 30, 2019	930,807	$ 2,405	3,590,056	(2,662,786)	1,132
Balances, in shares at Sep. 30, 2019		240,509
Balances at Mar. 31, 2019	832,335	$ 2,051	3,442,029	(2,611,745)	0
Balances, in shares at Mar. 31, 2019		205,111
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(36,764)			(36,764)
Common stock issued under "at the market" stock offering (in shares)		16,631
Common stock issued under "at the market" stock offering	48,887	$ 166	48,721
Common stock issued under stock-based compensation plans, net (in shares)		117
Common stock issued under stock-based compensation plans, net	1,988	$ 2	1,986
Balances at Jun. 30, 2019	846,446	$ 2,219	3,492,736	(2,648,509)	0
Balances, in shares at Jun. 30, 2019		221,859
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(14,277)			(14,277)
Other comprehensive income (loss)	1,132				1,132
Common stock issued for the extinguishment of Senior Notes (in shares)		4,452
Common stock issued for the extinguishment of Senior Notes	21,290	$ 44	21,246
Common stock issued under "at the market" stock offering (in shares)		14,220
Common stock issued under "at the market" stock offering	73,781	$ 142	73,639
Common stock issued under stock-based compensation plans, net (in shares)		(22)
Common stock issued under stock-based compensation plans, net	2,435	$ 0	2,435
Balances at Sep. 30, 2019	930,807	$ 2,405	3,590,056	(2,662,786)	1,132
Balances, in shares at Sep. 30, 2019		240,509
Balances at Dec. 31, 2019	667,004	$ 2,415	3,598,472	(2,933,747)	(136)
Balances, in shares at Dec. 31, 2019		241,529
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(11,900)			(11,900)
Other comprehensive income (loss)	206				206
Stock Issued During Period, Shares, Acquisitions							878
Stock Issued During Period, Value, Acquisitions						$ 5,295	$ 9	$ 5,286
Common stock issued under stock-based compensation plans, net (in shares)		1,179
Common stock issued under stock-based compensation plans, net	39	$ 12	27
Balances at Mar. 31, 2020	660,644	$ 2,436	3,603,785	(2,945,647)	70
Balances, in shares at Mar. 31, 2020		243,586
Balances at Dec. 31, 2019	667,004	$ 2,415	3,598,472	(2,933,747)	(136)
Balances, in shares at Dec. 31, 2019		241,529
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	13,747			13,747
Other comprehensive income (loss)	(26,176)
Balances at Sep. 30, 2020	664,227	$ 2,437	3,608,102	(2,920,000)	(26,312)
Balances, in shares at Sep. 30, 2020		243,745
Balances at Mar. 31, 2020	660,644	$ 2,436	3,603,785	(2,945,647)	70
Balances, in shares at Mar. 31, 2020		243,586
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	(1,209)			(1,209)
Other comprehensive income (loss)	(7,776)				(7,776)
Common stock issued under stock-based compensation plans, net (in shares)		146
Common stock issued under stock-based compensation plans, net	2,198	$ 1	2,197
Balances at Jun. 30, 2020	653,857	$ 2,437	3,605,982	(2,946,856)	(7,706)
Balances, in shares at Jun. 30, 2020		243,732
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	26,856			26,856
Other comprehensive income (loss)	(18,606)				(18,606)
Common stock issued under stock-based compensation plans, net (in shares)		13
Common stock issued under stock-based compensation plans, net	2,120	$ 0	2,120
Balances at Sep. 30, 2020	$ 664,227	$ 2,437	$ 3,608,102	$ (2,920,000)	$ (26,312)
Balances, in shares at Sep. 30, 2020		243,745