Employee compensation Restricted Stock Option Awards (Details 1) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013
Weighted-average grant date fair value
Tax deficiency related to vested stock awards	$ 0.1	$ 0.1	$ 0.2		$ 0.4
Restricted Stock Awards
Restricted stock awards
Outstanding at the beginning of the period (in shares)			1,799,000
Granted (in shares)			1,161,000
Forfeited (in shares)			(50,000)
Vested (in shares)			(527,000)	[1]
Outstanding at the end of the period (in shares)	2,383,000		2,383,000
Weighted-average grant date fair value
Outstanding at the beginning of the period (in dollars per share)			$ 19.17
Fair value per performance share			$ 25.75
Forfeited (in dollars per share)			$ 22.62
Vested (in dollars per share)			$ 17.70	[1]
Outstanding at the end of the period (in dollars per share)	$ 22.64		$ 22.64
Tax deficiency related to vested stock awards		$ 0.1			$ 0.4

[1] The vesting of certain restricted stock awards could result in federal and state income tax expense or benefits related to the difference between the market price of the common stock at the date of vesting and the date of grant. For the three and six months ended June 30, 2014, the Company's recognized income tax expense related to the vesting of restricted stock awards was immaterial. The Company recognized income tax expense of $0.1 million and $0.4 million during the three and six months ended June 30, 2013, respectively, related to restricted stock awards, which were recorded as adjustments to deferred income taxes.