v3.3.1.900
Consolidated Statements of Cash Flows - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Cash flows from operating activities:      
Net income $ 15,865 $ 30,244 $ 1,541
Adjustments to reconcile net income to net cash provided by operating activities:      
Depreciation and amortization expense 14,360 11,897 9,612
Bad debt expense 851 470 307
Loss on disposal of property and equipment 5 324 12
Stock-based compensation 17,494 10,549 5,506
Amortization of premiums and accretion of discounts on investments 594 565 282
Excess tax benefits from stock-based compensation (487) (259) (150)
Impairment of intangible assets 255 0 0
Deferred income taxes 6,564 (22,599) (66)
Changes in operating assets and liabilities:      
Accounts receivable (10,183) (4,882) (4,343)
Prepaid expenses and other assets (1,011) (3,456) 610
Accounts payable (3,293) 2,332 (100)
Accrued liabilities 3,339 1,622 437
Deferred revenues 21,378 14,817 11,281
Other noncurrent liabilities 229 (201) 152
Net cash provided by operating activities 65,960 41,423 25,081
Cash flows from investing activities:      
Purchases of investments (146,707) (157,660) (145,263)
Sales and maturities of investments 105,509 157,339 138,124
Purchases of property and equipment (20,051) (13,914) (13,650)
Capitalized software development costs (99) (98) 0
Release of restricted cash 0 0 114
Net cash used in investing activities (61,348) (14,333) (20,675)
Cash flows from financing activities:      
Proceeds from exercise of stock options 10,095 7,639 4,073
Proceeds from early exercise of stock options 0 0 40
Excess tax benefits from stock-based compensation 487 259 150
Principal payments under capital lease obligations 0 (805) (1,186)
Net cash provided by financing activities 10,582 7,093 3,077
Effect of exchange rate changes on cash and cash equivalents 0 (48) 1
Net increase in cash and cash equivalents 15,194 34,135 7,484
Cash and cash equivalents at beginning of period 76,504 42,369 34,885
Cash and cash equivalents at end of period 91,698 76,504 42,369
Supplemental disclosures of cash flow information      
Cash paid for interest expense 6 9 43
Cash paid for income taxes, net of refunds 995 347 390
Non-cash investing and financing activities      
Purchases of property and equipment recorded in accounts payable and accrued liabilities 0 1,399 487
Vesting of early exercised common stock options $ 19 $ 47 $ 262