Equity-based Incentive Plans (Details) (2006 Amended and Restated Equity Incentive Plan (2006 Plan), USD $)	0 Months Ended			12 Months Ended
	May 17, 2012	Dec. 31, 2013	May 18, 2006	Dec. 31, 2013 Stock options	Dec. 31, 2013 Performance shares Senior executives	Dec. 31, 2013 Performance shares Senior executives Minimum	Dec. 31, 2013 Performance shares Senior executives Maximum	Dec. 31, 2013 Restricted stock units	Dec. 31, 2012 Restricted stock units	Dec. 31, 2013 Restricted stock	Dec. 31, 2012 Restricted stock	Dec. 31, 2011 Restricted stock	Dec. 31, 2013 Deferred stock units	Dec. 31, 2012 Deferred stock units	Dec. 31, 2011 Deferred stock units
Equity-based Incentive Plans
Original number of shares authorized for issuance			16,000,000
Additional number of shares authorized for issuance	15,500,000
Shares available for issuance		12,000,000
Shares that may be issued					684,000
Factor used for granting of stock options and stock appreciation rights against the share limit of the awards that are not full value awards (in shares)		1
Factor used for granting of RSUs, DSUs, restricted and unrestricted stock awards and performance awards against the share limit of the awards that are full value awards		2.09
Vesting percentage				100.00%				100.00%
Vesting period				6 months	2 years			2 years
Term of award				5 years
Options exercise price as a percentage of fair value of common stock				100.00%
Eligible age for retirement								59 years 6 months
Performance period					3 years
Awards earned as percentage of annual compensation						0.00%	100.00%
Transition period one					1 year
Transition period two					2 years
Earned (in shares)					95,000
Number of RSU's
Outstanding at the beginning of the period (in shares)								1,269,307
Granted (in shares)								1,293,140	1,422,448	35,000	27,000	160,000	53,000	79,000	42,000
Vested (in shares)								(170,398)	(143,666)
Forfeited (in shares)								(112,406)	(9,475)
Outstanding at the end of the period (in dollars per share)								2,279,643	1,269,307
Weighted Average Grant Date Fair Value
Outstanding, at the beginning of the period (in dollars per share)								$ 11.87
Granted (in dollars per share)								$ 18.16	$ 11.95
Vested (in dollars per share)								$ 17.74	$ 12.65
Forfeited (in dollars per share)								$ 12.48	$ 11.92
Outstanding, at the end of the period (in dollars per share)								$ 14.97	$ 11.87
Aggregate Intrinsic Value
Aggregate Intrinsic Value								$ 44,544,000	$ 17,428,000
Unrecognized Compensation
Unrecognized Compensation								22,197,000	12,318,000
Weighted average remaining life before vesting of the outstanding RSU's								1 year 4 months 24 days
Fair value of vesting during the period								$ 3,300,000	$ 1,800,000
Number of withheld shares								63,000	49,000