Stock Options and Other Equity-Based Incentive Instruments (Details) (USD $)	6 Months Ended	9 Months Ended
	Jun. 30, 2012	Sep. 30, 2012
Stock option activity
Outstanding at December 31, 2011, Number of shares	1,250,935	1,250,935
Outstanding at December 31, 2011, Weighted Average Exercise Price	$ 17.18	$ 17.18
Options granted, Number of Shares		179,000
Options granted, Weighted Average Exercise Price		$ 15.28
Options granted, Weighted Average Fair Value on Date of Grant		$ 6.63
Options exercised, Number of shares	(3,065)	(17,000)
Options exercised, Weighted Average Exercise Price		$ 12.01
Options forfeited, Number of Shares
Options forfeited, Weighted Average Exercise Price
Outstanding at September 30, 2012, Number of Shares		1,412,935
Outstanding at September 30, 2012, Weighted Average Exercise Price		$ 17.00
Maximum [Member]
Stock option activity
Outstanding at December 31, 2011, Option Price per Share	$ 25.91	$ 25.91
Options granted, Option Price per Share		$ 15.34
Options exercised, Option Price per Share		$ 11.72
Options forfeited, Option Price per Share
Outstanding at September 30, 2012, Option Price per Share		$ 25.91
Minimum [Member]
Stock option activity
Outstanding at December 31, 2011, Option Price per Share	$ 11.72	$ 11.72
Options granted, Option Price per Share		$ 14.76
Options exercised, Option Price per Share		$ 12.13
Options forfeited, Option Price per Share
Outstanding at September 30, 2012, Option Price per Share		$ 11.72