Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 100,535	$ 85,046
Short-term marketable securities	35,867	46,750
Accounts receivable, net of allowance for doubtful accounts of $966 and $919 as of June 30, 2019 and December 31, 2018, respectively	62,548	59,155
Inventory	9,688	10,087
Prepaid expenses and other current assets	7,826	8,567
Income taxes receivable	2,852	5,757
Total current assets	219,316	215,362
Property and equipment, net	248,816	228,001
Goodwill	128,752	128,752
Other intangible assets, net	18,116	19,850
Long-term marketable securities	14,268	23,579
Operating lease assets	12,249	0
Other long-term assets	4,010	3,441
Total assets	645,527	618,985
Current liabilities
Accounts payable	21,230	17,411
Accrued compensation	14,068	18,130
Accrued liabilities and other	10,422	16,702
Current operating lease liabilities	3,296	0
Income taxes payable	2,417	491
Total current liabilities	51,433	52,734
Long-term operating lease liabilities	9,218	0
Long-term deferred tax liabilities	21,745	20,162
Other long-term liabilities	5,018	4,592
Total liabilities	87,414	77,488
Shareholders' equity
Preferred stock, $0.001 par value, authorized 10,000,000 shares; issued and outstanding 0 shares as of each of June 30, 2019 and December 31, 2018	0	0
Common stock, $0.001 par value, authorized 150,000,000 shares; issued and outstanding 26,882,097 and 26,984,747 shares as of June 30, 2019 and December 31, 2018, respectively	27	27
Additional paid-in capital	262,952	258,502
Retained earnings	303,628	291,460
Accumulated other comprehensive loss	(8,494)	(8,492)
Total shareholders' equity	558,113	541,497
Total liabilities and shareholders' equity	$ 645,527	$ 618,985