Significant Accounting Policies (Earnings Per Share) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		0 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Mar. 08, 2012 2011 Stock Repurchase Program [Member]	May 02, 2011 2011 Stock Repurchase Program [Member]	Sep. 30, 2013 2011 Stock Repurchase Program [Member]	Dec. 31, 2012 2011 Stock Repurchase Program [Member]
Significant Accounting Policies [Line Items]
Common stock equivalents (in shares)	1,009,000	432,000	903,000	996,000
Anti-dilutive securities excluded from computation of diluted earnings per share (in shares)	812,000	4,342,000	1,019,000	1,819,000
Stock repurchase program authorized amount					$ 323.7	$ 300.0
Stock repurchase program remaining authorized repurchase amount							$ 280.0	$ 350.0