Stock-Based Compensation (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2009 item
Restricted Stock Unit Awards
Share-Based Compensation
Number of shares of common stock exchanged for each award	1
Aggregate number of shares approved	5,188,333
Unrecognized compensation cost related to the unvested awards	$ 2,400,000
Weighted average period over which unrecognized compensation cost is expected to be recognized	2 years
Number of Shares
Granted and unvested, beginning of period (in shares)	1,141,666
Vested (in shares)	(849,999)
Granted (in shares)	246,668
Forfeited (in shares)	(176,667)
Total granted and unvested (in shares)	361,668	1,141,666
Approved for grant (in shares)	957,500
Total awarded and unvested, end of period (in shares)	1,319,168
Weighted Average Grant Date Fair Value
Total Granted and Unvested, beginning of period, weighted average grant date fair value (in dollars per share)	$ 18.12
Vested, weighted average grant date fair value (in dollars per share)	$ 19.91
Granted, weighted average grant date fair value (in dollars per share)	$ 19.87	$ 14.39	$ 19.03
Forfeited, weighted average grant date fair value (in dollars per share)	$ 13.66
Total Granted and Unvested, end of period, weighted average grant date fair value (in dollars per share)	$ 17.30	$ 18.12
Aggregate Intrinsic Value
Total Granted and Unvested, beginning of period, aggregate intrinsic value	15,641,000
Vested, aggregate intrinsic value	17,505,000
Granted, aggregate intrinsic value	6,487,000
Total Granted and Unvested, aggregate intrinsic value	9,512,000	15,641,000
Approved for grant, aggregate intrinsic value	25,182,000
Total Awarded and Unvested, end of period, aggregate intrinsic value	34,694,000
Vesting schedule of outstanding unvested restricted stock awards
2014 (in shares)	286,668
2015 (in shares)	342,500
2016 (in shares)	202,500
2017 (in shares)	442,500
2018 (in shares)	36,000
2019 (in shares)	9,000
Total (in shares)	1,319,168
Number of unvested stock awards that will vest subject to the satisfaction of service-based requirements (in shares)	150,000
Number of unvested stock awards that will vest subject to the satisfaction of service-based requirements and the achievement of performance metrics (in shares)	1,169,168
Restricted Stock Unit Awards | Awarded in 2009 and 2010
Share-Based Compensation
Number of restricted stock units for which performance targets established (in shares)	181,668
Restricted Stock Unit Awards | Awarded in 2013
Share-Based Compensation
Number of restricted stock units for which performance targets established (in shares)	65,000
Number of Shares
Approved for grant (in shares)	312,500
Stock options
Share-Based Compensation
Aggregate number of shares approved	2,535,465
Unrecognized compensation cost related to the unvested awards	979,000
Weighted average period over which unrecognized compensation cost is expected to be recognized	2 years
Vesting schedule of outstanding unvested restricted stock awards
Term of Stock Options	10 years
Number of Shares
Total Granted and Outstanding, beginning of period (in shares)	1,315,465
Granted (in shares)	200,000
Exercised (in shares)	(80,465)
Forfeited (in shares)	(140,000)
Total granted and outstanding (in shares)	1,295,000
Approved for grant (in shares)	800,000
Total Awarded and Unvested, end of period (in shares)	2,095,000	1,315,465
Weighted Average Grant Date Fair Value
Total Granted and Outstanding, beginning of period, grant date value (in dollars per share)	$ 9.72
Granted, grant date value (in dollars per share)	$ 7.90	$ 5.65	$ 9.31
Exercised, grant date value (in dollars per share)	$ 6.71
Forfeited, grant date value (in dollars per share)	$ 6.76
Total Granted and Outstanding, end of period, grant date value (in dollars per share)	$ 9.94	$ 9.72
Weighted Average Exercise Price
Total granted and outstanding, beginning of period, weighted average exercise price (in dollars per share)	$ 18.91
Granted, weighted average exercise price (in dollars per share)	$ 20.80
Exercised, weighted average exercise price (in dollars per share)	$ 13.16
Total Granted and Outstanding, weighted average exercise price (in dollars per share)	$ 20.20
Approved for grant, weighted average exercise price (in dollars per share)	$ 12.61
Total Awarded and Outstanding, end of period, weighted average exercise price (in dollars per share)	$ 17.30	$ 18.91
Number of vested and exercisable stock options (in shares)	1,045,000
Vested and exercisable stock options, weighted average exercise price (in dollars per share)	$ 20.41
Number of unvested stock option awards that will vest subject to the satisfaction of service-based requirements (in shares)	50,000
Number of unvested stock option awards that will vest subject to the satisfaction of service-based requirements and the achievement of performance metrics (in shares)	1,000,000
Intrinsic value of outstanding stock options	$ 7,900,000
Weighted average remaining contractual term of outstanding stock options	5 years 7 months 6 days
Number of installments for vesting of stock awards				5
Stock options | Awarded in 2009
Vesting schedule of outstanding unvested restricted stock awards
Number of stock option awards subject to achievement of pre-tax income performance targets (in shares)	150,000
Key assumptions used in estimating the grant date fair values of stock option awards granted
Number of options for which fair value assumptions used	150,000	150,000	150,000
Risk-free interest rate (as a percent)	0.48%	0.88%	2.74%
Expected life of options	3 years 7 months 6 days	4 years 4 months 24 days	6 years 6 months
Expected volatility of underlying stock (as a percent)	51.00%	53.89%	46.94%
Stock options | Awarded in 2013
Vesting schedule of outstanding unvested restricted stock awards
Number of stock option awards subject to achievement of pre-tax income performance targets (in shares)	50,000
Number of Shares
Approved for grant (in shares)	170,000
Key assumptions used in estimating the grant date fair values of stock option awards granted
Number of options for which fair value assumptions used	50,000
Risk-free interest rate (as a percent)	1.64%
Expected life of options	5 years 8 months 12 days
Expected volatility of underlying stock (as a percent)	51.81%
Stock options | Awarded in 2012
Key assumptions used in estimating the grant date fair values of stock option awards granted
Number of options for which fair value assumptions used		15,000
Risk-free interest rate (as a percent)		1.12%
Expected life of options		7 years 3 months 18 days
Expected volatility of underlying stock (as a percent)		50.59%
Stock options | Awarded in 2011 -1
Key assumptions used in estimating the grant date fair values of stock option awards granted
Number of options for which fair value assumptions used			140,000
Risk-free interest rate (as a percent)			1.13%
Expected life of options			6 years
Expected volatility of underlying stock (as a percent)			49.86%
Stock options | Awarded in 2011 -2
Key assumptions used in estimating the grant date fair values of stock option awards granted
Number of options for which fair value assumptions used			30,000
Risk-free interest rate (as a percent)			1.25%
Expected life of options			6 years 6 months
Expected volatility of underlying stock (as a percent)			48.70%
Stock options | Awarded in 2011 -3
Key assumptions used in estimating the grant date fair values of stock option awards granted
Number of options for which fair value assumptions used			40,465
Risk-free interest rate (as a percent)			0.89%
Expected life of options			5 years
Expected volatility of underlying stock (as a percent)			51.62%
Plan
Share-Based Compensation
Number of shares authorized for grant	6,900,000
Number of shares available for future grant (in shares)	330,286