Stock-Based Awards and Programs (Details 2) (Stock Options, USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 Y	Mar. 31, 2011 Y
Stock options
Outstanding, balance at the beginning of the period (in shares)	190,300	267,400
Exercised (in shares)	(27,000)
Outstanding, balance at the end of the period (in shares)	163,300	267,400
Exercisable (in shares)	128,500	205,600
Weighted Average Exercise Price
Outstanding, balance at the beginning of the period (in dollars per option)	$ 21.56	$ 21.69
Exercised (in dollars per share)	$ 18.12
Outstanding, balance at the end of the period (in dollars per option)	$ 22.13	$ 21.69
Exercisable (in dollars per share)	$ 23.15	$ 22.73
Aggregate intrinsic value
Aggregate intrinsic value of unexercised options		$ 0.2
Weighted-average remaining contractual life of outstanding options (in years)	3.9	5.8
Range of exercise prices, low end of range (in dollars per share)	$ 18.36	$ 18.12
Range of exercise prices, high end of range (in dollars per share)	$ 23.81	$ 23.81
Total unrecognized compensation expense related to non-vested options and related dividend equivalents granted under the plan		0.1
Recognition period, low end of range (in years)		1
Recognition period, high end of range (in years)		2
Maximum
Aggregate intrinsic value
Aggregate intrinsic value of unexercised options	0.1
Total unrecognized compensation expense related to non-vested options and related dividend equivalents granted under the plan	$ 0.1
Recognition period	1