Other Data (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Net income	$ 69,771	$ 23,092	$ 85,571
Reconciling items to taxable income:
Depreciation and amortization	64,775	46,426	38,260
Gain or loss on disposition of depreciable assets	(27,581)	1,570	(32,103)
Impairments	0	0	121
Straight-line rent	(3,049)	(4,551)	(7,101)
Receivable allowances	2,470	1,680	2,067
Stock-based compensation	(1,699)	1,855	1,301
Other	842	6,552	2,236
Reconciling items to taxable income, total	35,758	53,532	4,781
Taxable income	105,529	76,624	90,352
Dividends paid	$ 150,266	$ 142,327	$ 131,759