Consolidated Statements Of Stockholders' Equity (Deficit) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total [Member]
Stock Issued During Period, Value, Employee Stock Purchase Plan		$ 1	$ 12,914
Stock Issued During Period, Value, Conversion of Convertible Securities	$ 0
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt			0
Balance at Dec. 31, 2016		324	16,987,488	$ (18,184,954)	$ (3,453)	$ (1,200,595)
Net income	457,248			457,248
Other Comprehensive Income (Loss), Net of Tax	512				512
Stock-based compensation			55,362
Repurchase of common stock			(621,173)
Balance at Dec. 31, 2017		325	16,437,135	(17,694,790)	(2,941)	(1,260,271)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			2,544	32,916
Stock Issued During Period, Value, Employee Stock Purchase Plan		1	12,835
Stock Issued During Period, Value, Conversion of Convertible Securities	26
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt			(159,618)
Net income	582,489			582,489
Other Comprehensive Income (Loss), Net of Tax	130				130
Stock-based compensation			54,574
Repurchase of common stock			(638,152)
Balance at Dec. 31, 2018	$ (1,385,474)	352	15,706,774	(17,089,789)	(2,811)	(1,385,474)
Balance, shares at Dec. 31, 2018	120,037
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			0	22,512
Stock Issued During Period, Value, Employee Stock Purchase Plan		1	13,151
Stock Issued During Period, Shares, Conversion of Convertible Securities	26,100
Stock Issued During Period, Value, Conversion of Convertible Securities	$ 0
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt			0
Net income	612,299			612,299
Other Comprehensive Income (Loss), Net of Tax	190				190
Stock-based compensation			52,316
Repurchase of common stock			(782,583)
Balance at Dec. 31, 2019	$ (1,490,100)	$ 353	14,989,658	(16,477,490)	$ (2,621)	$ (1,490,100)
Balance, shares at Dec. 31, 2019	116,716
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			$ 0	$ 0