Share-Based Compensation (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Restricted Stock [Member]
Summary of restricted stock and PBRS activity
Beginning Balance, Weighted-Average Grant Date Fair Value	$ 20.36	$ 21.51	$ 24.59
Beginning Balance, Shares	572,022	478,499	390,810
Granted, Shares	168,050	191,850	157,900
Granted, Weighted-Average Grant Date Fair Value	$ 20.46	$ 22.70	$ 19.30
Vested, Shares	(219,571)	(91,212)	(65,961)
Vested, Weighted-Average Grant Date Fair Value	$ 18.26	$ 31.31	$ 34.42
Forfeited or Cancelled, Shares	(4,150)	(7,115)	(4,250)
Forfeited or Cancelled, Weighted-Average Grant Date Fair Value	$ 24.80	$ 20.81	$ 22.55
Ending Balance, Weighted-Average Grant Date Fair Value	$ 21.25	$ 20.36	$ 21.51
Ending Balance, Shares	516,351	572,022	478,499
PBRS [Member]
Summary of restricted stock and PBRS activity
Beginning Balance, Weighted-Average Grant Date Fair Value	$ 15.36	$ 33.02	$ 20.77
Beginning Balance, Shares	416	18,830	174,927
Granted, Shares			29,547
Granted, Weighted-Average Grant Date Fair Value			$ 35.31
Vested, Shares	(416)	(18,414)
Vested, Weighted-Average Grant Date Fair Value	$ 15.36	$ 33.42
Forfeited or Cancelled, Shares			(126,550)
Forfeited or Cancelled, Weighted-Average Grant Date Fair Value			$ 15.36
Ending Balance, Weighted-Average Grant Date Fair Value		$ 15.36	$ 33.02
Ending Balance, Shares		416	18,830