Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Intangible assets, accumulated amortization	$ 15.8	$ 15.3
Intangible liabilities, accumulated amortization	$ 13.8	$ 13.5
Preferred stock, par value (in USD per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	91,669
Preferred stock, shares outstanding	0	91,669
Common stock, par value (in USD per share)	$ 2.50	$ 2.50
Common stock, shares authorized	30,000,000	30,000,000
Common stock, shares issued	17,769,746	17,102,777
Common stock, shares outstanding	17,769,746	17,102,777