Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Consolidated Balance Sheets [Abstract]
Properties and equipment, accumulated depreciation	$ 254,499	$ 248,370
Lease right of use assets, accumulated amortization	5,450
Identifiable intangible assets, accumulated amortization	$ 33,803	$ 33,284
Capital stock - authorized	80,000,000	80,000,000
Capital stock - par value	$ 1	$ 1
Capital stock - issued	35,520,908	35,311,418
Treasury stock	19,661,407	19,438,358