Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 121,568	$ 85,046
Short-term marketable securities	23,642	46,750
Accounts receivable, net of allowance for doubtful accounts of $1,001 and $919 as of September 30, 2019 and December 31, 2018, respectively	64,069	59,155
Inventory	9,448	10,087
Prepaid expenses and other current assets	8,038	8,567
Income taxes receivable	2,852	5,757
Total current assets	229,617	215,362
Property and equipment, net	252,579	228,001
Goodwill	128,752	128,752
Other intangible assets, net	18,258	19,850
Long-term marketable securities	9,783	23,579
Operating lease assets	12,008	0
Other long-term assets	3,902	3,441
Total assets	654,899	618,985
Current liabilities
Accounts payable	18,668	17,411
Accrued compensation	12,926	18,130
Accrued liabilities and other	13,133	16,702
Current operating lease liabilities	3,364	0
Income taxes payable	6,717	491
Total current liabilities	54,808	52,734
Long-term operating lease liabilities	9,006	0
Long-term deferred tax liabilities	21,750	20,162
Other long-term liabilities	5,238	4,592
Total liabilities	90,802	77,488
Shareholders' equity
Preferred stock, $0.001 par value, authorized 10,000,000 shares; issued and outstanding 0 shares as of each of September 30, 2019 and December 31, 2018	0	0
Common stock, $0.001 par value, authorized 150,000,000 shares; issued and outstanding 26,759,109 and 26,984,747 shares as of September 30, 2019 and December 31, 2018, respectively	27	27
Additional paid-in capital	265,178	258,502
Retained earnings	309,536	291,460
Accumulated other comprehensive loss	(10,644)	(8,492)
Total shareholders' equity	564,097	541,497
Total liabilities and shareholders' equity	$ 654,899	$ 618,985