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 income	$ 5,876	$ 14,929	$ 4,896
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	75,926	75,235	70,527
Amortization of debt discount and premium	1,239	1,105	171
Equity-based compensation expense (net of amounts capitalized)	13,290	10,735	11,515
Losses on debt extinguishment and redemption		587	10,144
Gains on capital lease terminations			(11,643)
Gains - equipment transactions and other, net	(4,833)	(7,674)	(4,866)
Deferred income taxes	24,679	9,224	7,709
Changes in operating assets and liabilities:
Accounts receivable	(4,161)	(3,183)	1,119
Prepaid expenses and other current assets	1,146	(2,923)	(2,898)
Deposits and other assets	1,111	(336)	(221)
Accounts payable, accrued liabilities and other long-term liabilities	(2,571)	10,268	(2,644)
Net cash provided by operating activities	111,702	107,967	83,809
Cash flows from investing activities:
Purchases of property and equipment	(45,801)	(45,234)	(35,582)
Proceeds from asset sales			111
Net cash used in investing activities	(45,801)	(45,234)	(35,471)
Cash flows from financing activities:
Net proceeds from issuance of 2022 secured notes--net of debt costs of $1,202 and $1,397, respectively		124,267	248,603
Extinguishment of 2021 unsecured notes		(10,775)
Redemption of 2018 secured notes			(251,280)
Dividends paid	(81,657)	(68,210)	(66,314)
Principal payments of capital lease obligations	(11,201)	(12,466)	(20,215)
Principal payments on installment payment agreement	(3,802)	(21,203)	(670)
Purchases of common stock	(1,829)	(4,492)	(39,394)
Proceeds from exercises of common stock options	1,222	1,220	423
Net cash (used in) provided by financing activities	(97,267)	8,341	(128,847)
Effect of exchange rate changes on cash	4,058	(346)	(3,690)
Net (decrease) increase in cash and cash equivalents	(27,308)	70,728	(84,199)
Cash and cash equivalents, beginning of year	274,319	203,591	287,790
Cash and cash equivalents, end of year	247,011	274,319	203,591
Supplemental disclosures of cash flow information:
Cash paid for interest	47,032	37,125	44,383
Cash paid for income taxes	441	143	577
Non-cash investing and financing activities:
Capital lease obligations incurred	22,595	18,439	25,794
PP&E obtained for installment payment agreement	9,027	5,521	21,873
Fair value of equipment acquired in leases		2,110	595
Non-cash component of network equipment obtained in exchange transactions	$ 3,861	$ 7,739	$ 8,156