Employee Benefit Plans (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended										12 Months Ended
	Dec. 31, 2013 D Y	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Employee Thrift Plan [Member]	Dec. 31, 2012 Employee Thrift Plan [Member]	Dec. 31, 2011 Employee Thrift Plan [Member]	Dec. 31, 2013 Salary Deferral Plan [Member]	Dec. 31, 2012 Salary Deferral Plan [Member]	Jan. 01, 1997 Separation Plan [Member] Y week	May 05, 2004 Special Separation Benefit Plan [Member] Y	Dec. 31, 2013 Change Of Control Contracts [Member] Y	Dec. 31, 2013 Plan 401k [Member] Y
Defined Benefit Plan Disclosure [Line Items]
Contribution of shares, common stock				111,995	95,598	71,742
Recognized stock compensation expense	$ 16.1	$ 11.4	$ 10.0	$ 6.0	$ 5.5	$ 4.3
Liability recorded under deferral plan							3.6	2.8
Service period, years									20	20
Maximum period benefit, weeks									104
Age limit										65
Separation benefit plans expense	$ 2.4	$ 2.2	$ 1.9
Employee contract period, years											3
Employment contract period extension, years	1
Grace period following the first anniversary	30
Multiple for determination compensation											2.9
Additional period for 401k, years												3