Contingencies - Narrative (Details) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended								0 Months Ended		1 Months Ended	3 Months Ended		1 Months Ended			1 Months Ended
	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)	Dec. 31, 2008 USD ($)	Aug. 31, 2009	Aug. 31, 2009 Securities Finance USD ($)	Mar. 31, 2015 Securities Finance USD ($)	Oct. 31, 2009 Foreign Exchange USD ($)	Mar. 31, 2015 Foreign Exchange USD ($)	Mar. 31, 2015 Putative Class Action claim	Jan. 31, 2014 Transition Management claim	Mar. 31, 2015 Transition Management USD ($)	Mar. 31, 2015 Transition Management Legal Reserve USD ($)	Jan. 31, 2014 Transition Management Regulatory Matter USD ($)	Jan. 31, 2014 Transition Management Regulatory Matter GBP (£)	Mar. 31, 2015 Investment Servicing USD ($) claim
Loss Contingencies [Line Items]
Legal reserves																	$ 358
Number of lawsuits from related participants of agency securities lending program									2
Loss contingency, damages sought, value										125
Litigation reserve											11.0					2.7				4.3
Realized loss on sales of securities											10
Actual damages asserted by attorney general												100
Number of pending claims														2						1
Estimated indirect foreign exchange revenue	68	246	285	248	331	336	369	462
Loss Contingency, Estimate of Possible Loss													335
Loss Contingency, Estimate Of Possible Loss, net of tax													150
Settlement, amount													$ 925.0					$ 37.8	£ 22.9
Claims settled															6