Stock Incentive Plans (Details) (USD $)	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	May 21, 2014	Sep. 30, 2014
Stock Incentive Plan
Options outstanding and exercisable, intrinsic value	$ 0
Weighted average remaining contractual term	7 months
Restricted common stock and restricted stock units
Stock Incentive Plan
Outstanding (in shares)	752,701	781,644
Restricted common stock granted (in shares)	514,507
Granted (in dollars per share)	$ 12.58	$ 9.70	$ 9.82
Aggregate fair value on the vest date of restricted common stock awards, vested during the year	6,600,000	9,600,000	6,200,000
Stock based compensation expense, taxes	3,100,000	2,500,000	1,800,000
Stock based compensation expense, net of tax	5,600,000	4,500,000	3,300,000
Nonvested awards, compensation cost not yet recognized	10,800,000
Nonvested awards, compensation cost not yet recognized, period for recognition	1 year 9 months 18 days
Pretax compensation cost related to non-vested performance based stock awards and units	1,800,000
Expense reversal			569,000
Stock Based Compensation Expense Taxes Reversed			$ 310,000
Performance-based restricted common stock awards or units | Officers | Share Vesting, Period 1
Stock Incentive Plan
Granted upon change in control	100.00%
Performance Based Restricted Stock
Stock Incentive Plan
Employee service share based compensation non vested performance based awards total compensation cost not yet recognized, shares or units	65,000
Performance based restricted stock unit
Stock Incentive Plan
Outstanding (in shares)	776,500	409,100
Restricted common stock granted (in shares)	395,900
Granted (in dollars per share)	$ 12.14
Employee service share based compensation non vested performance based awards total compensation cost not yet recognized, shares or units	98,475
2014 Employee Stock Plan
Stock Incentive Plan
Share-based compensation arrangement by share-based payment award, number of additional shares authorized				3,250,000
Number of shares available for grant	3,672,764
Common stock, capital shares reserved for future issuance				3,757,925
2005 Employee Stock Plan
Stock Incentive Plan
Number of shares available for grant				507,925	0
2005 Employee Stock Plan | Performance-based restricted common stock awards or units
Stock Incentive Plan
Outstanding (in shares)	382,600	393,900
Restricted common stock granted (in shares)	395,900	432,300
2005 Employee Stock Plan | Performance-based restricted common stock awards or units | Officers
Stock Incentive Plan
Equity instruments other than options vested in period share of common stock to be paid	1
Directors Stock Plan, 2007 Plan
Stock Incentive Plan
Number of shares available for grant	67,135
Restricted common stock granted (in shares)	32,506
Number of shares authorized	240,080
Directors Stock Plan, 2007 Plan | Restricted common stock and restricted stock units
Stock Incentive Plan
Award vesting period	3 years
All stock plans other than 2014 Employee stock plan, 2005 Employee stock plan and 2007 Directors stock plan | Employee Non Employee Director Stock Option
Stock Incentive Plan
Expiration period	10 years
Minimum
Stock Incentive Plan
Share-based compensation arrangement by share-based payment award, award vesting rights, percentage	0.00%
Maximum
Stock Incentive Plan
Share-based compensation arrangement by share-based payment award, award vesting rights, percentage	125.00%