Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jun. 30, 2018	$ 318,843	$ 279	$ 132,198	$ 211,494	$ (17,717)	$ (7,411)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	15,170	0	0	15,170	0	0
Other comprehensive income (loss)	(452)	0	0	0	0	(452)
Exercise of stock options	128	0	(126)	0	254	0
Issuance of deferred shares	0	0	(6,306)	0	6,306	0
Treasury shares sold to Employee Stock Purchase Plan	235	0	25	0	210	0
Open market purchases of treasury shares	(5,190)	0	0	0	(5,190)	0
Treasury shares purchased to satisfy tax withholding obligations	(1,685)	0	0	0	(1,685)	0
Stock-based compensation expense	9,045	0	9,045	0	0	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 31, 2019	336,094	279	134,836	226,664	(17,822)	(7,863)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2018	323,590	279	131,889	217,731	(18,230)	(8,079)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	8,933	0	0	8,933	0	0
Other comprehensive income (loss)	216	0	0	0	0	216
Issuance of deferred shares	0	0	(366)	0	366	0
Treasury shares sold to Employee Stock Purchase Plan	82	0	6	0	76	0
Treasury shares purchased to satisfy tax withholding obligations	(34)	0	0	0	(34)	0
Stock-based compensation expense	3,307	0	3,307	0	0	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 31, 2019	336,094	279	134,836	226,664	(17,822)	(7,863)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jun. 30, 2019	351,957	279	137,712	239,476	(17,759)	(7,751)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(27,352)	0	0	(27,352)	0	0
Other comprehensive income (loss)	(975)	0	0	0	0	(975)
Issuance of deferred shares	0	0	(8,563)	0	8,563	0
Treasury shares sold to Employee Stock Purchase Plan	243	0	42	0	201	0
Open market purchases of treasury shares	(17,045)	0	0	0	(17,045)	0
Treasury shares purchased to satisfy tax withholding obligations	(3,517)	0	0	0	(3,517)	0
Stock-based compensation expense	8,115	0	8,115	0	0	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 31, 2020	311,426	279	137,306	212,124	(29,557)	(8,726)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2019	322,795	279	135,057	217,619	(22,538)	(7,622)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(5,495)	0	0	(5,495)	0	0
Other comprehensive income (loss)	(1,104)	0	0	0	0
Issuance of deferred shares	0	0	(77)	0	77	0
Treasury shares sold to Employee Stock Purchase Plan	86	0	24	0	62	0
Open market purchases of treasury shares	(7,132)	0	0	0	(7,132)	0
Treasury shares purchased to satisfy tax withholding obligations	(26)	0	0	0	(26)	0
Stock-based compensation expense	2,302	0	2,302	0	0	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Mar. 31, 2020	$ 311,426	$ 279	$ 137,306	$ 212,124	$ (29,557)	$ (8,726)