Employee Stock Purchase Plan Stock Options and Warrants - Stock Option Activity (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total intrinsic value of stock options exercised	$ 1,649	$ 3,472	$ 9,433
Cash received from stock option exercises	3,281	3,325	7,197
Excess tax benefit from the exercise of stock options	259	877	3,122
Number of Shares
Beginning balance (in shares)	3,535
Granted (in shares)	348	128	844
Exercised (in shares)	(368)
Forfeited/expired (in shares)	(507)
Outstanding at December 31 (in shares)	3,008	3,535
Exercisable (in shares)	2,075
Ending vested and expected to vest (in shares)	2,991
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 12.14	$ 12.55
Granted (in dollars per share)	$ 12.08
Exercised (in shares)	$ 10.10
Forfeited/expired (in shares)	$ 16.43
Outstanding at December 31 (in dollars per share)	$ 12.14	$ 12.55
Exercisable (in dollars per share)	$ 11.73
Ending vested and expected to vest (in dollars per share)	$ 12.14
Outstanding, Remaining Contractual Term	2 years 11 months 1 day
Outstanding, Intrinsic Value	10,823
Exercisable, Remaining Contractual Term	1 year 10 months 10 days
Exercisable, Intrinsic Value	8,312
Ending vested and expected to vest, Remaining Contractual Term	2 years 10 months 29 days
Ending vested and expected to vest, Intrinsic Value	$ 10,772
Weighted average grant-date fair value of options granted	$ 4.01	$ 5.31	$ 5.28