Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 47,829	$ 83,343
Short-term investments	29,854	3,963
Accounts receivable, net	38,554	32,386
Prepaid expenses and other	9,310	9,578
Inventory	1,229	1,708
Total current assets	126,776	130,978
Non-current assets:
Property and equipment, net	9,759	10,354
Operating lease right-of-use assets	16,773	0
Goodwill	133,031	133,031
Intangible assets, net	4,167	5,417
Deferred income tax assets	46,229	46,484
Other non-current assets	1,338	1,448
Total non-current assets	211,297	196,734
Total assets	338,073	327,712
Current liabilities:
Accounts payable	3,795	2,010
Accrued compensation and benefits	8,793	11,348
Accrued taxes	1,785	1,822
Deferred revenue	27,938	26,106
Operating lease liabilities	5,261	0
Other current liabilities	2,567	3,662
Total current liabilities	50,139	44,948
Non-current liabilities:
Asset retirement obligations	6,681	6,513
Operating lease liabilities	12,084	0
Other non-current liabilities	669	1,697
Total non-current liabilities	19,434	8,210
Total liabilities	69,573	53,158
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred stock	0	0
Common stock	2	2
Additional paid-in capital	89,415	90,559
Accumulated other comprehensive loss	(1,394)	(1,301)
Retained earnings	180,477	185,294
Total stockholders’ equity	268,500	274,554
Total liabilities and stockholders' equity	$ 338,073	$ 327,712