Significant Accounting Policies (Earnings Per Share) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		0 Months Ended		3 Months Ended	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 08, 2012 2011 Stock Repurchase Program [Member]	May 02, 2011 2011 Stock Repurchase Program [Member]	Mar. 31, 2014 2011 Stock Repurchase Program [Member]	Dec. 31, 2013 2011 Stock Repurchase Program [Member]
Significant Accounting Policies [Line Items]
Common stock equivalents (in shares)	1,120,000	981,000
Anti-dilutive securities excluded from computation of diluted earnings per share (in shares)	961,000	1,678,000
Stock repurchase program authorized amount			$ 323.7	$ 300.0
Stock repurchase program remaining authorized repurchase amount					$ 280.0	$ 280.0