Stock-Based Awards and Programs (Details 2) (Stock Options, USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Stock options
Outstanding, balance at the beginning of the period (in shares)	163,300	190,300
Exercised (in shares)	40,200	27,000
Outstanding, balance at the end of the period (in shares)	123,100	163,300
Exercisable (in shares)	123,100	128,500
Weighted Average Exercise Price
Outstanding, balance at the beginning of the period (in dollars per option)	$ 22.13	$ 21.56
Exercised (in dollars per share)	$ 21.66	$ 18.12
Outstanding, balance at the end of the period (in dollars per option)	$ 23.19	$ 22.13
Exercisable (in dollars per share)	$ 23.19	$ 23.15
Intrinsic value of unexercised options if closing price of stock is less than the exercise price (in dollars per share)	$ 0
Aggregate intrinsic value
Aggregate intrinsic value of unexercised options		$ 0.1
Weighted-average remaining contractual life of outstanding options	2 years 7 months 6 days	3 years 8 months 12 days
Range of exercise prices, low end of range (in dollars per share)	$ 21.79	$ 18.36
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
Recognition period		7 months 6 days
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