Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 62,593	$ 36,707
Short-term marketable securities	57,561	57,424
Accounts receivable, net of allowance for doubtful accounts of $949 and $757 as of September 30, 2018 and December 31, 2017, respectively	62,131	51,503
Inventory	9,608	11,271
Prepaid expenses and other current assets	8,639	6,267
Income taxes receivable		1,832
Total current assets	200,532	165,004
Property and equipment, net	210,053	166,440
Goodwill	128,752	128,504
Other intangible assets, net	19,713	19,084
Long-term marketable securities	33,224	37,034
Other long-term assets	3,590	2,672
Total assets	595,864	518,738
Liabilities and shareholders' equity
Accounts payable	17,300	15,876
Accrued compensation	14,462	12,100
Accrued liabilities and other	14,843	8,408
Short-term debt obligations		5,000
Income taxes payable	2,763	2,371
Total current liabilities	49,368	43,755
Long-term income taxes payable	2,181	2,181
Long-term deferred tax liabilities	8,732	6,966
Other long-term liabilities	4,377	4,621
Total liabilities	64,658	57,523
Shareholders' equity
Preferred stock, $0.001 par value, authorized 10,000,000 shares; issued and outstanding 0 shares as of each of September 30, 2018 and December 31, 2017
Common stock, $0.001 par value, authorized 150,000,000 shares; issued and outstanding 27,068,068 and 26,828,651 shares as of September 30, 2018 and December 31, 2017, respectively	27	27
Additional paid-in capital	254,957	241,725
Retained earnings	283,460	224,697
Accumulated other comprehensive loss	(7,238)	(5,234)
Total shareholders' equity	531,206	461,215
Total liabilities and shareholders' equity	$ 595,864	$ 518,738