Consolidated Condensed Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Assets:
Accumulated depreciation on revenue earning equipment	$ 3,587,031	$ 3,596,102
Accumulated depreciation on operating property and equipment	$ (1,006,105)	$ (991,117)
Shareholders' equity:
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	3,800,917	3,800,917
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.5	$ 0.5
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares outstanding	53,184,496	53,335,386