Stock-Based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended			6 Months Ended	1 Months Ended						1 Months Ended
	Jun. 30, 2012 plan	Jun. 30, 2011	Jun. 30, 2012 LTIP	Jun. 30, 2012 Stock Option	Mar. 31, 2012 Stock Option Various employees, including the company's named executive officers	Jan. 31, 2012 Stock Option Chief financial officer	Mar. 31, 2012 Restricted Stock	Mar. 31, 2012 Restricted Stock Various employees, including the company's named executive officers	Jan. 31, 2012 Restricted Stock Various employees, including the company's named executive officers	Jan. 03, 2012 Restricted Stock Various employees, including the company's named executive officers employee	Mar. 31, 2012 Restricted Stock Eligible members of the Board of Directors	Mar. 31, 2012 Performance Awards
Stock-Based Compensation
Share-based compensation arrangements, number of plans	2
Options granted (in shares)					145,354	23,734
Grant date fair value of options granted (in dollars per share)					$ 8.42	$ 9.48
Vesting period					3 years	4 years		5 years	5 years		3 years	2 years 9 months 7 days
New shares issued upon the exercise of vested stock options				36,992
Total intrinsic value of options exercised (in dollars)				$ 0.4
Stock awards granted (in shares)								56,980	17,562		24,024	41,755
Grant date fair value of stock awards (in dollars per share)								$ 17.48	$ 19.46		$ 17.48	$ 17.48
Number of employees to whom awards covering shares of common stock granted										2
Shares vested from prior grant							25,248
Shares received as payment for withholding taxes due by holders of awards							6,186
Stock-based compensation expense recognized (in dollars)	1.3	1.0
Net reduction in expense related to a change in the estimated forfeiture rates for the various awards and a change in the estimated number of performance shares that are expected to be earned (in dollars)		0.2
Total unrecognized stock-based compensation cost, net of estimated forfeitures (in dollars)			$ 6.1