Stock-Based Compensation Plans (Details) (USD $)	6 Months Ended			12 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Stock Options [Member]	Dec. 31, 2013 Stock Options [Member]	Jun. 30, 2014 Performance-based Shares [Member]	Jun. 30, 2014 Restricted Shares [Member]	Jun. 30, 2014 Restricted and Performance-based Shares [Member]	Jun. 30, 2013 Restricted and Performance-based Shares [Member]	Jun. 30, 2014 Restricted and Performance-based Shares [Member] Employees [Member]	Jun. 30, 2014 Restricted and Performance-based Shares [Member] Executives [Member]	Jun. 30, 2014 Restricted and Performance-based Shares [Member] Directors [Member]	Jun. 30, 2014 Restricted and Performance-based Shares [Member] Age 60 [Member]	Jun. 30, 2014 Restricted and Performance-based Shares [Member] Age 63 [Member]	Jun. 30, 2014 Restricted and Performance-based Shares [Member] Age65 [Member]
Options, shares [Roll Forward]
Outstanding, beginning of period (in shares)			16,875
Expired (in shares)			0
Exercised (in shares)			(7,000)
Forfeited, other (in shares)			0
Outstanding, end of period (in shares)			9,875	16,875
Options exercisable, end of period (in shares)			9,875
Options, weighted average exercise price [Roll Forward]
Outstanding, beginning of period (in dollars per share)			$ 12.14
Expired (in dollars per share)			$ 0
Exercised (in dollars per share)			$ 13.76
Forfeited, other (in dollars per share)			$ 0
Outstanding, end of period (in dollars per share)			$ 10.99	$ 12.14
Options exercisable, end of period (in dollars per share)			$ 10.99
Options, additional disclosures [Abstract]
Outstanding, weighted average remaining contractual term, beginning of period			0 years 10 months 24 days	1 year
Outstanding, weighted average remaining contractual term, end of period			0 years 10 months 24 days	1 year
Options exercisable, weighted average remaining contractual term, end of period			0 years 10 months 24 days
Aggregate intrinsic value of outstanding stock options			$ 300,000
Total intrinsic value of options exercised			200,000
Options granted (in shares)			0
Restricted and Performance Stock Grants [Abstract]
Measuring period for performance-based shares					3 years
Award vesting rights					Selected executives and other key personnel are granted performance awards whose vesting is contingent upon meeting various performance measures with a retention feature. Performance-based shares are subject to a three-year measuring period and the achievement of performance targets and, depending upon the achievement of such performance targets, they may become vested on the third anniversary of the date of grant.	Restricted shares granted to employees become fully vested upon the third anniversary of the date of grant; and for selected key executives, certain additional restricted share grants vest 25% upon the attainment of age 60, 25% upon the attainment of age 63 and become fully vested upon the attainment of age 65. Restricted shares granted to directors become fully vested upon the first anniversary of the date of grant.
Vesting percentage (in hundredths)												25.00%	25.00%	100.00%
Estimated forfeitures (in hundredths)									5.00%	0.00%	0.00%
Restricted and performance-based stock, shares [Roll Forward]
Beginning of period (in shares)							630,600
Granted (in shares)							36,518
Vested (in shares)							(18,075)
Forfeited (in shares)							(4,300)
End of period (in shares)							644,743
Restricted and performance-based stock, weighted average grant date fair value per share [Roll Forward]
Beginning of period (in dollars per share)							$ 19.47
Granted (in dollars per share)							$ 37.48
Vested (in dollars per share)							$ 26.35
Forfeited (in dollars per share)							$ 17.57
End of period (in dollars per share)							$ 20.40
Compensation expense, gross	2,397,000	1,494,000					2,000,000	1,100,000
Compensation expense, net of tax							1,300,000	700,000
Unamortized compensation expense							$ 8,200,000
Weighted average period of recognition for unrecognized compensation expense									4 years 10 months 24 days		0 years 9 months 18 days