Employee Benefit Plans (Details 5) (Employee Stock Ownership Plan, USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee Stock Ownership Plan
Employee stock ownership plan
Minimum employee age required to participate in the plan	21 years
Period of service to be completed to participate in the plan	12 months
Minimum number of working hours required for employees to participate in the plan	1000 hours
Outstanding balance of loan	$ 24.4
Compensation expense	1.7	1.5	1.5
Number of shares to be released each December 31	126,280
Number of shares of common stock unallocated	2,020,490
Unallocated shares, fair value	$ 29.9