Shareholders' Equity - Treasury Stock (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended		17 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	May 02, 2012
Equity [Abstract]
Number of shares authorized to be repurchased				5,000,000
Stock Repurchased During Period, Shares	600,000		1,800,000
Payments for Repurchase of Common Stock	$ 2.5	$ 4.9	$ 9.0
Remaining number of shares authorized to be repurchased	3,200,000		3,200,000
Average price per share of treasury stock acquired and held	$ 23.31
Movement in Treasury Stock [Roll Forward]
Balance as of December 31, 2012 (shares)	1,563,321
Purchases (shares)	616,581
Exercise of stock options (shares)	0
Restricted stock grants and other (shares)	(656,413)
401(k) matching contribution (shares)	(378,511)
Balance as of September 30, 2013 (shares)	1,144,978		1,144,978