CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Cumulative adjustment from adoption of recent accounting pronouncements (refer to Note 1)	Cumulative adjustment from adoption of recent accounting pronouncements (refer to Note 1) Retained Earnings
Beginning balance (in shares) at Mar. 31, 2019		29,141,000
Beginning balance at Mar. 31, 2019	$ 1,045,130	$ 291	$ 178,227	$ 889,266	$ (22,654)	$ (1,069)	$ (1,069)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation (in shares)		1,000
Stock-based compensation	3,424		3,424
Shares issued upon vesting (in shares)		4,000
Exercise of stock options (in shares)		46,000
Exercise of stock options	2,773	$ 1	2,772
Shares withheld for taxes	(374)		(374)
Repurchases of common stock (in shares)		(227,000)
Repurchases of common stock	(35,005)	$ (2)		(35,003)
Net income (loss)	(19,351)			(19,351)
Total other comprehensive income (loss)	(249)				(249)
Ending balance (in shares) at Jun. 30, 2019		28,965,000
Ending balance at Jun. 30, 2019	995,279	$ 290	184,049	833,843	(22,903)
Beginning balance (in shares) at Mar. 31, 2019		29,141,000
Beginning balance at Mar. 31, 2019	1,045,130	$ 291	178,227	889,266	(22,654)	$ (1,069)	$ (1,069)
Increase (Decrease) in Stockholders' Equity
Net income (loss)	260,052
Total other comprehensive income (loss)	(449)
Ending balance (in shares) at Dec. 31, 2019		27,982,000
Ending balance at Dec. 31, 2019	1,123,747	$ 280	188,713	957,857	(23,103)
Beginning balance (in shares) at Jun. 30, 2019		28,965,000
Beginning balance at Jun. 30, 2019	995,279	$ 290	184,049	833,843	(22,903)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation (in shares)		3,000
Stock-based compensation	5,075		5,075
Shares issued upon vesting (in shares)		73,000
Shares issued upon vesting	618	$ 1	617
Exercise of stock options (in shares)		3,000
Exercise of stock options	186		186
Shares withheld for taxes	(5,370)		(5,370)
Repurchases of common stock (in shares)		(1,069,000)
Repurchases of common stock	(155,400)	$ (11)		(155,389)
Net income (loss)	77,810			77,810
Total other comprehensive income (loss)	(1,894)				(1,894)
Ending balance (in shares) at Sep. 30, 2019		27,975,000
Ending balance at Sep. 30, 2019	916,304	$ 280	184,557	756,264	(24,797)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation (in shares)		1,000
Stock-based compensation	4,221		4,221
Shares issued upon vesting (in shares)		3,000
Exercise of stock options (in shares)		3,000
Exercise of stock options	186		186
Shares withheld for taxes	(251)		(251)
Net income (loss)	201,593			201,593
Total other comprehensive income (loss)	1,694				1,694
Ending balance (in shares) at Dec. 31, 2019		27,982,000
Ending balance at Dec. 31, 2019	1,123,747	$ 280	188,713	957,857	(23,103)
Beginning balance (in shares) at Mar. 31, 2020		27,999,000
Beginning balance at Mar. 31, 2020	1,140,120	$ 280	191,451	973,948	(25,559)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation (in shares)		1,000
Stock-based compensation	3,618		3,618
Shares issued upon vesting (in shares)		1,000
Exercise of stock options (in shares)		4,000
Exercise of stock options	247		247
Shares withheld for taxes	(90)		(90)
Net income (loss)	(7,973)			(7,973)
Total other comprehensive income (loss)	1,006				1,006
Ending balance (in shares) at Jun. 30, 2020		28,005,000
Ending balance at Jun. 30, 2020	1,136,928	$ 280	195,226	965,975	(24,553)
Beginning balance (in shares) at Mar. 31, 2020		27,999,000
Beginning balance at Mar. 31, 2020	$ 1,140,120	$ 280	191,451	973,948	(25,559)
Increase (Decrease) in Stockholders' Equity
Repurchases of common stock (in shares)	0
Net income (loss)	$ 349,117
Total other comprehensive income (loss)	14,269
Ending balance (in shares) at Dec. 31, 2020		28,152,000
Ending balance at Dec. 31, 2020	1,520,121	$ 282	208,064	1,323,065	(11,290)
Beginning balance (in shares) at Jun. 30, 2020		28,005,000
Beginning balance at Jun. 30, 2020	1,136,928	$ 280	195,226	965,975	(24,553)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation (in shares)		1,000
Stock-based compensation	4,019		4,019
Shares issued upon vesting (in shares)		60,000
Shares issued upon vesting	698	$ 1	697
Exercise of stock options (in shares)		16,000
Exercise of stock options	1,134		1,134
Shares withheld for taxes	(6,964)		(6,964)
Net income (loss)	101,554			101,554
Total other comprehensive income (loss)	5,595				5,595
Ending balance (in shares) at Sep. 30, 2020		28,082,000
Ending balance at Sep. 30, 2020	1,242,964	$ 281	194,112	1,067,529	(18,958)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation (in shares)		1,000
Stock-based compensation	9,900		9,900
Shares issued upon vesting (in shares)		1,000
Exercise of stock options (in shares)		68,000
Exercise of stock options	4,202	$ 1	4,201
Shares withheld for taxes	(149)		(149)
Net income (loss)	255,536			255,536
Total other comprehensive income (loss)	7,668				7,668
Ending balance (in shares) at Dec. 31, 2020		28,152,000
Ending balance at Dec. 31, 2020	$ 1,520,121	$ 282	$ 208,064	$ 1,323,065	$ (11,290)