Retirement Plans and Profit Sharing Arrangements (Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary of unrealized losses included in other comprehensive income
Net unrealized defined benefit losses at the beginning of the period	$ (46)	$ (91)	$ (75)
Net gains (losses)	(37)	71	(23)
Prior service credit	(1)	(2)	(2)
Income tax (provision) benefit	13	(24)	9
Net unrealized defined benefit losses at the end of the period	$ (71)	$ (46)	$ (91)