Stock Options and Other Equity-Based Incentive Instruments (Details) (USD $)	6 Months Ended
	Jun. 30, 2012
Stock option activity
Outstanding at December 31, 2011, Number of shares	1,250,935
Outstanding at December 31, 2011, Weighted Average Exercise Price	$ 17.18
Options granted, Number of Shares	159,000
Options granted, Weighted Average Exercise Price	$ 15.34
Options granted, Weighted Average Fair Value on Date of Grant	$ 6.66
Options exercised, Number of shares	0
Options exercised, Weighted Average Exercise Price	$ 12.01
Options forfeited, Number of Shares
Options forfeited, Weighted Average Exercise Price
Outstanding at June 30, 2012, Number of Shares	1,392,935
Outstanding at June 30, 2012, Weighted Average Exercise Price	$ 17.03
Maximum [Member]
Stock option activity
Outstanding at December 31, 2011, Option Price per Share	$ 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 June 30, 2012, Option Price per Share	$ 25.91
Minimum [Member]
Stock option activity
Outstanding at December 31, 2011, Option Price per Share	$ 11.72
Options granted, Option Price per Share	$ 15.34
Options exercised, Option Price per Share	$ 12.13
Options forfeited, Option Price per Share
Outstanding at June 30, 2012, Option Price per Share	$ 11.72