CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total ATNI Stockholders' Equity	Common Stock	Treasury Stock, at cost	Additional Paid In Capital	Retained Earnings	Accumulated Other Comprehensive Income/(Loss)	Non-Controlling Interests	Total
Increase (Decrease) in Stockholders' Equity
Cumulative effect adjustment due to adoption of new accounting	$ 1,488			$ 26	$ 1,665	$ (203)	$ 1,147	$ 2,635
Balance, beginning of period at Dec. 31, 2017	688,727	$ 170	$ (36,110)	167,973	552,948	3,746	141,496	830,223
Increase (Decrease) in Stockholders' Equity
Issuance of shares of common stock upon exercise of stock options	571			571				571
Purchase of shares of common stock	(4,175)		(4,175)					(4,175)
Stock-based compensation	5,071			5,071				5,071
Dividends declared on common stock	(8,115)				(8,115)		(15,487)	(23,602)
Repurchase of non-controlling interests	1,273			1,273			(6,469)	(5,196)
Comprehensive income:
Net income (loss)	18,682				18,682		10,705	29,387
Other comprehensive income (loss)	(5,867)					(5,867)		(5,867)
Comprehensive income	12,815						10,705	23,520
Balance, end of period at Sep. 30, 2018	697,655	170	(40,285)	174,914	565,180	(2,324)	131,392	829,047
Balance, beginning of period at Jun. 30, 2018	683,085	170	(40,268)	172,170	550,872	141	136,424	819,509
Increase (Decrease) in Stockholders' Equity
Issuance of shares of common stock upon exercise of stock options	72			72				72
Purchase of shares of common stock	(17)		(17)					(17)
Stock-based compensation	1,392			1,392				1,392
Dividends declared on common stock	(2,714)				(2,714)		(2,511)	(5,225)
Repurchase of non-controlling interests	1,280			1,280			(6,408)	(5,128)
Comprehensive income:
Net income (loss)	17,022				17,022		3,887	20,909
Other comprehensive income (loss)	(2,465)					(2,465)		(2,465)
Comprehensive income	14,557						3,887	18,444
Balance, end of period at Sep. 30, 2018	697,655	170	(40,285)	174,914	565,180	(2,324)	131,392	829,047
Balance, beginning of period at Dec. 31, 2018	695,387	172	(48,547)	181,778	563,593	(1,609)	127,937	823,324
Increase (Decrease) in Stockholders' Equity
Issuance of shares of common stock upon exercise of stock options	62			62				62
Purchase of shares of common stock	(1,837)		(1,837)					(1,837)
Stock-based compensation	4,606			4,606			275	4,881
Dividends declared on common stock	(8,178)				(8,178)		(5,788)	(13,966)
Repurchase of non-controlling interests							(1,353)	(1,353)
Investments made by minority shareholders in consolidated affiliates							488	488
Comprehensive income:
Net income (loss)	(1,052)				(1,052)		8,657	7,605
Other comprehensive income (loss)	(905)					(905)		(905)
Comprehensive income	(1,957)						8,657	6,700
Balance, end of period at Sep. 30, 2019	688,083	172	(50,384)	186,446	554,363	(2,514)	130,216	818,299
Balance, beginning of period at Jun. 30, 2019	689,683	172	(50,125)	185,112	555,806	(1,282)	128,858	818,541
Increase (Decrease) in Stockholders' Equity
Issuance of shares of common stock upon exercise of stock options	62			62				62
Purchase of shares of common stock	(259)		(259)					(259)
Stock-based compensation	1,272			1,272			275	1,547
Dividends declared on common stock	(2,828)				(2,828)		(1,885)	(4,713)
Repurchase of non-controlling interests							(491)	(491)
Comprehensive income:
Net income (loss)	1,385				1,385		3,459	4,844
Other comprehensive income (loss)	(1,232)					(1,232)		(1,232)
Comprehensive income	153						3,459	3,612
Balance, end of period at Sep. 30, 2019	$ 688,083	$ 172	$ (50,384)	$ 186,446	$ 554,363	$ (2,514)	$ 130,216	$ 818,299