Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 62,927	$ 83,343
Short-term investments	18,868	3,963
Accounts receivable, net	36,721	32,386
Prepaid expenses and other	8,666	9,578
Inventory	1,436	1,708
Total current assets	128,618	130,978
Non-current assets:
Property and equipment, net	9,823	10,354
Operating lease right-of-use assets	16,965	0
Goodwill	133,031	133,031
Intangible assets, net	4,792	5,417
Deferred income tax assets	45,967	46,484
Other non-current assets	1,406	1,448
Total non-current assets	211,984	196,734
Total assets	340,602	327,712
Current liabilities:
Accounts payable	3,358	2,010
Accrued compensation and benefits	9,158	11,348
Accrued taxes	1,812	1,822
Deferred revenue	28,091	26,106
Operating lease liabilities	5,286	0
Other current liabilities	2,845	3,662
Total current liabilities	50,550	44,948
Non-current liabilities:
Asset retirement obligations	6,615	6,513
Deferred revenue	470	476
Operating lease liabilities	12,204	0
Other non-current liabilities	229	1,221
Total non-current liabilities	19,518	8,210
Total liabilities	70,068	53,158
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred stock	0	0
Common stock	2	2
Additional paid-in capital	88,266	90,559
Accumulated other comprehensive loss	(1,361)	(1,301)
Retained earnings	183,627	185,294
Total stockholders’ equity	270,534	274,554
Total liabilities and stockholders' equity	$ 340,602	$ 327,712