Consolidated Statement of Shareholders' Equity - USD ($) $ in Thousands	Warrant Common Stock [Member]	Warrant Warrant	Warrant	Common Stock [Member]	Warrant	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
BALANCES at Dec. 31, 2012				$ 226,035	$ 17,946	$ (36,996)	$ (5,904)	$ 201,081
BALANCES (in Shares) at Dec. 31, 2012				95,844,000
Consolidated net income (loss)						52,362		52,362
Excercise of stock options				$ 2,634				$ 2,634
Excercise of stock options (in Shares)				630,000				630,000
Employee stock purchase plan issuances				$ 588				$ 588
Employee stock purchase plan issuances (in Shares)				61,000
Restricted stock units				$ 579				579
Restricted stock units (in Shares)				34,000
Stock-based compensation expense				$ 6,471				6,471
Foreign currency translation loss							(6,463)	(6,463)
Excess tax benefit - stock compensation				2,928				2,928
BALANCES at Dec. 31, 2013				$ 239,235	17,946	15,366	(12,367)	$ 260,180
BALANCES (in Shares) at Dec. 31, 2013				96,569,000				96,569,186
Consolidated net income (loss)								$ 9,494
BALANCES at Mar. 31, 2014								$ 273,715
BALANCES (in Shares) at Mar. 31, 2014								96,697,545
BALANCES at Dec. 31, 2013				$ 239,235	17,946	15,366	(12,367)	$ 260,180
BALANCES (in Shares) at Dec. 31, 2013				96,569,000				96,569,186
Consolidated net income (loss)								$ 8,238
BALANCES at Jun. 30, 2014								$ 284,209
BALANCES (in Shares) at Jun. 30, 2014								104,088,199
BALANCES at Dec. 31, 2013				$ 239,235	17,946	15,366	(12,367)	$ 260,180
BALANCES (in Shares) at Dec. 31, 2013				96,569,000				96,569,186
Consolidated net income (loss)								$ (4,095)
BALANCES at Sep. 30, 2014								$ 309,391
BALANCES (in Shares) at Sep. 30, 2014								107,330,516
BALANCES at Dec. 31, 2013				$ 239,235	$ 17,946	15,366	(12,367)	$ 260,180
BALANCES (in Shares) at Dec. 31, 2013				96,569,000				96,569,186
Consolidated net income (loss)						13,884		$ 13,884
Excercise of stock options				$ 8,013				$ 8,013
Excercise of stock options (in Shares)				4,226,000				4,226,000
Employee stock purchase plan issuances				$ 829				$ 829
Employee stock purchase plan issuances (in Shares)				73,000
Restricted stock units				$ 1,188				1,188
Restricted stock units (in Shares)				16,000
Stock-based compensation expense				$ 6,564				6,564
Foreign currency translation loss							(1,704)	(1,704)
Excess tax benefit - stock compensation				29,517				29,517
Unrealized holding loss on available-for-sale securities							(1,124)	(1,124)
Convertible note conversions				$ 30,789				30,789
Convertible note conversions (in Shares)				3,659,000
Exercise of warrants	$ 26,117	$ (17,946)	$ 8,171
Exercise of warrants (in Shares)	7,192,000
BALANCES at Dec. 31, 2014				$ 342,252		29,250	(15,195)	$ 356,307
BALANCES (in Shares) at Dec. 31, 2014				111,735,000				111,734,901
BALANCES at Mar. 31, 2014								$ 273,715
BALANCES (in Shares) at Mar. 31, 2014								96,697,545
Consolidated net income (loss)								$ (1,256)
BALANCES at Jun. 30, 2014								$ 284,209
BALANCES (in Shares) at Jun. 30, 2014								104,088,199
Consolidated net income (loss)								$ (12,333)
BALANCES at Sep. 30, 2014								$ 309,391
BALANCES (in Shares) at Sep. 30, 2014								107,330,516
Consolidated net income (loss)								$ 17,979
BALANCES at Dec. 31, 2014				$ 342,252		29,250	(15,195)	$ 356,307
BALANCES (in Shares) at Dec. 31, 2014				111,735,000				111,734,901
Consolidated net income (loss)								$ 37,538
BALANCES at Mar. 31, 2015								$ 442,175
BALANCES (in Shares) at Mar. 31, 2015								114,332,873
BALANCES at Dec. 31, 2014				$ 342,252		29,250	(15,195)	$ 356,307
BALANCES (in Shares) at Dec. 31, 2014				111,735,000				111,734,901
Consolidated net income (loss)								$ 70,046
BALANCES at Jun. 30, 2015								$ 535,946
BALANCES (in Shares) at Jun. 30, 2015								119,199,049
BALANCES at Dec. 31, 2014				$ 342,252		29,250	(15,195)	$ 356,307
BALANCES (in Shares) at Dec. 31, 2014				111,735,000				111,734,901
Consolidated net income (loss)								$ 118,013
Excercise of stock options (in Shares)								2,519,000
BALANCES at Sep. 30, 2015								$ 584,502
BALANCES (in Shares) at Sep. 30, 2015								119,313,203
BALANCES at Dec. 31, 2014				$ 342,252		29,250	(15,195)	$ 356,307
BALANCES (in Shares) at Dec. 31, 2014				111,735,000				111,734,901
Consolidated net income (loss)						150,798		$ 150,798
Excercise of stock options				$ 10,503				$ 10,503
Excercise of stock options (in Shares)				2,514,000				2,519,000
Employee stock purchase plan issuances				$ 1,413				$ 1,413
Employee stock purchase plan issuances (in Shares)				66,000
Restricted stock units				$ 3,814				3,814
Restricted stock units (in Shares)				16,000
Stock-based compensation expense				$ 9,183				9,183
Foreign currency translation loss							(2,051)	(2,051)
Excess tax benefit - stock compensation				47,997				47,997
Unrealized holding loss on available-for-sale securities							104	104
Convertible note conversions				$ 43,497				43,497
Convertible note conversions (in Shares)				5,096,000
BALANCES at Dec. 31, 2015				$ 458,659		180,048	(17,142)	$ 621,565
BALANCES (in Shares) at Dec. 31, 2015				119,427,000				119,427,471
BALANCES at Mar. 31, 2015								$ 442,175
BALANCES (in Shares) at Mar. 31, 2015								114,332,873
Consolidated net income (loss)								$ 32,508
BALANCES at Jun. 30, 2015								$ 535,946
BALANCES (in Shares) at Jun. 30, 2015								119,199,049
Consolidated net income (loss)								$ 47,967
BALANCES at Sep. 30, 2015								$ 584,502
BALANCES (in Shares) at Sep. 30, 2015								119,313,203
Consolidated net income (loss)								$ 32,785
BALANCES at Dec. 31, 2015				$ 458,659		$ 180,048	$ (17,142)	$ 621,565
BALANCES (in Shares) at Dec. 31, 2015				119,427,000				119,427,471