CONSOLIDATED BALANCE SHEETS (Parentheticals) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
ASSETS
Accumulated depreciation	$ 371,323	$ 367,205
Accumulated amortization	$ 563,511	$ 535,627
Shareholders' equity:
Common stock, par value (per share)	$ 1.00	$ 1.00
Common stock, shares authorized	500,000	500,000
Common stock, shares outstanding	43,638	44,647