CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net (loss) income	$ (15,306)	$ 13,979	$ 80,246
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation, amortization and accretion	11,624	12,963	13,970
Deferred income tax expense (benefit)	25,390	6,926	(55,018)
Stock based compensation	3,688	854	1,868
Provisions for doubtful accounts, service credits and other	1,035	761	1,290
Adjustments of non-cash transaction taxes	(807)	(270)	(686)
(Gain) Loss on disposals of property and equipment	(6)	2	(793)
Changes in assets and liabilities:
Accounts receivable	(9,648)	(1,790)	1,041
Prepaid expenses, intangible assets and other assets	274	843	658
Accounts payable, accrued liabilities and other	(3,267)	1,083	(3,556)
Deferred revenue	2,579	2,110	2,817
Net cash provided by operating activities	15,556	37,461	41,837
Cash flows from investing activities:
Purchases of property and equipment, net of proceeds from disposals of property and equipment	(9,214)	(6,254)	(5,565)
Net cash used in investing activities	(9,214)	(6,254)	(5,565)
Cash flows from financing activities:
Cash distributions to stockholders	(15,234)	(10,287)	(13,976)
Purchase of common stock (including commissions)	(10,023)	(6,489)	(15,008)
Proceeds from issuance of common stock under the Employee Stock Purchase Plan	256	53	0
Employee stock based compensation tax withholding	0	0	(3,825)
Net cash used in financing activities	(25,001)	(16,723)	(32,809)
Net (decrease) increase in cash and cash equivalents	(18,659)	14,484	3,463
Cash and cash equivalents, beginning of period	125,816	111,332	107,869
Cash and cash equivalents, end of period	107,157	125,816	111,332
Supplemental disclosure:
Income taxes paid	$ 2,620	$ 695	$ 1,521