CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Retained Earnings
Balance at beginning of period at Dec. 31, 2018	$ 394,567		$ 270,447		$ 124,120
Balance at beginning of period (in shares) at Dec. 31, 2018		43,864
Exercise of common stock options	9,502		9,502
Exercise of common stock options (in shares)		592
Restricted stock, net of forfeitures and shares withheld for taxes	(1,146)		(1,146)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)		23
Stock-based compensation	16,324		16,324
Net income	10,151				10,151
Balance at end of period at Mar. 31, 2019	429,398		295,127		134,271
Balance at end of period (in shares) at Mar. 31, 2019		44,479
Balance at beginning of period at Dec. 31, 2019	612,517		380,079		232,438
Balance at beginning of period (in shares) at Dec. 31, 2019		45,476
Impact upon adoption of new accounting standard (Note 2)	(388)				(388)
Exercise of common stock options	19,320		19,320
Exercise of common stock options (in shares)		539
Restricted stock, net of forfeitures and shares withheld for taxes	(4,893)		(4,893)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)		20
Stock-based compensation	23,263		23,263
Other comprehensive income	158			$ 158
Net income	24,057				24,057
Balance at end of period at Mar. 31, 2020	$ 674,034		$ 417,769	$ 158	$ 256,107
Balance at end of period (in shares) at Mar. 31, 2020		46,035