Stock-based Compensation (Stock Options) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2011
Granted, shares	14,716
Exercised, shares	(357,703)
Stock Options [Member]
Outstanding at beginning of period, shares	3,839,197
Granted, shares	0
Forfeited, shares	(12,356)
Expired, shares	(10,796)
Exercised, shares	(357,703)
Outstanding at end of period, shares	3,458,342
Exercisable at end of period, shares	2,973,498
Outstanding at beginning of period, weighted average exercise price	$ 19.54
Granted, weighted average exercise price
Forfeited, weighted average exercise price	$ 18.56
Expired, weighted average exercise price	$ 23.13
Exercised, weighted average exercise price	$ 15.56
Outstanding at end of period, weighted average exercise price	$ 19.95
Exercisable at end of period, weighted average exercise shares	$ 20.28
Outstanding at end of period, weighted average remaining life (years)	5.4
Exercisable at end of period, weighted average remaining life (years)	4.9
Outstanding at end of period, aggregate intrinsic value	$ 10,975
Exercisable at end of period, aggregate intrinsic value	$ 8,997