Nature of Operations (Details) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares	Sep. 30, 2020 USD ($) $ / shares	Jun. 30, 2020 USD ($) $ / shares	Mar. 31, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($) $ / shares	Sep. 30, 2019 USD ($) $ / shares	Jun. 30, 2019 USD ($) $ / shares	Mar. 31, 2019 USD ($) $ / shares	Dec. 31, 2020 USD ($) cell_site $ / shares	Dec. 31, 2019 USD ($) $ / shares	Dec. 31, 2018 USD ($) $ / shares
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Number of cell towers built | cell_site									223
Prepaid expenses and other	$ 9,631				$ 11,178				$ 9,631	$ 11,178
Deferred tax liabilities	24,088				27,311				24,088	27,311
Retained earnings	539,783				430,010				539,783	430,010
Property, plant and equipment, net	440,427				363,087				440,427	363,087
Property, plant and equipment	127,602				110,676				127,602	110,676
Depreciation and amortization									48,703	46,786	$ 44,390
Income tax (benefit) expense									(586)	173	(1,343)
Net Income (Loss) Attributable to Parent	$ 49,275	$ 34,921	$ 29,248	$ 13,279	$ 14,543	$ 14,354	$ 13,149	$ 13,910	$ 126,723	$ 55,956	$ 46,595
Basic - Income from discontinued operations, net of tax (in dollars per share) | $ / shares	$ 0.96	$ 0.67	$ 0.59	$ 0.27	$ 0.30	$ 0.27	$ 0.23	$ 0.27	$ 2.49	$ 1.07	$ 0.90
Diluted - Income from discontinued operations, net of tax (in dollars per share) | $ / shares	$ 0.95	$ 0.67	$ 0.59	$ 0.27	$ 0.30	$ 0.27	$ 0.23	$ 0.27	$ 2.48	$ 1.07	$ 0.89
Correction of Error
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Prepaid expenses and other					$ 2,700					$ 2,700
Deferred tax liabilities					700					700
Retained earnings					2,000					2,000
Property, plant and equipment, net					1,400					1,400
Property, plant and equipment					400					400
Depreciation and amortization					1,400					1,400
Income tax (benefit) expense					400					400
Net Income (Loss) Attributable to Parent					$ 1,000					$ 1,000
Basic - Income from discontinued operations, net of tax (in dollars per share) | $ / shares					$ 0.02					$ 0.02
Diluted - Income from discontinued operations, net of tax (in dollars per share) | $ / shares					$ 0.02					$ 0.02