Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 62,605	$ 36,707
Short-term marketable securities	57,619	57,424
Accounts receivable, net of allowance for doubtful accounts of $982 and $757 as of June 30, 2018 and December 31, 2017, respectively	55,928	51,503
Inventory	9,590	11,271
Prepaid expenses and other current assets	7,678	6,267
Income taxes receivable		1,832
Total current assets	193,420	165,004
Property and equipment, net	197,339	166,440
Goodwill	128,752	128,504
Other intangible assets, net	18,521	19,084
Long-term marketable securities	24,636	37,034
Other long-term assets	3,519	2,672
Total assets	566,187	518,738
Liabilities and shareholders' equity
Accounts payable	20,038	15,876
Accrued compensation	13,822	12,100
Accrued liabilities and other	9,885	8,408
Short-term debt obligations		5,000
Income taxes payable	637	2,371
Total current liabilities	44,382	43,755
Long-term income taxes payable	2,181	2,181
Long-term deferred tax liabilities	8,583	6,966
Other long-term liabilities	4,788	4,621
Total liabilities	59,934	57,523
Shareholders' equity
Preferred stock, $0.001 par value, authorized 10,000,000 shares; issued and outstanding 0 shares as of each of June 30, 2018 and December 31, 2017
Common stock, $0.001 par value, authorized 150,000,000 shares; issued and outstanding 27,026,394 and 26,828,651 shares as of June 30, 2018 and December 31, 2017, respectively	27	27
Additional paid-in capital	250,063	241,725
Retained earnings	262,522	224,697
Accumulated other comprehensive loss	(6,359)	(5,234)
Total shareholders' equity	506,253	461,215
Total liabilities and shareholders' equity	$ 566,187	$ 518,738