Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares outstanding	64,481,110	63,820,126
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Treasury stock, shares	454,577	317,103
Finite-Lived Intangible Assets, Accumulated Amortization	$ 44,100	$ 40,300