Equity Incentive Compensation Plans (Stock Options) (Details 2) (USD $)	0 Months Ended		6 Months Ended
	Jun. 30, 2013		Jun. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Options vested and expected to vest, number of shares	1,383,778		1,383,778
Options vested and expected to vest, weighted average exercise price	$ 33.73		$ 33.73
Options vested and expected to vest, aggregate intrinsic value	$ 13,465,000	[1]	$ 13,465,000	[1]
Options vested and expected to vest, weighted average remaining contractual term (years)	3 years 7 months 4 days
Stock options activity
Outstanding at the beginning of the period (in shares)			1,387,592
Granted (in shares)			0
Exercised (in shares)			(3,000)
Canceled/expired (in shares)			0
Outstanding at the end of the period (in shares)	1,384,592		1,384,592
Stock options, weighted average exercise price
Outstanding at the beginning of the period (in dollars per share)			$ 33.71
Granted (in dollars per share)			$ 0.00
Exercised (in dollars per share)			$ 21.58
Canceled/expired (in dollars per share)			$ 0.00
Outstanding at the end of the period (in dollars per share)	$ 33.74		$ 33.74
Stock options, aggregate intrinsic value
Outstanding at the beginning of the period			4,681,000	[1]
Exercised			76,000	[1]
Outstanding at the end of the period	13,465,000	[1]	13,465,000	[1]
Stock options, exercisable
Options exercisable, weighted average exercise price	$ 32.29		$ 32.29
Options exercisable, weighted average remaining contractual term (years)	3 years 2 months 13 days
Options exercisable, aggregate intrinsic value	13,465,000	[1]	13,465,000	[1]
Options outstanding at the end of the period (in shares)	1,278,372		1,278,372
Total unrecognized compensation cost	$ 2,000,000		$ 2,000,000
Period of recognition of unrecognized compensation cost (in years)	2 years 9 months
Stock options, weighted average remaining contractual term
Outstanding options, weighted average remaining contractual term (years)	3 years 7 months 4 days

[1] The intrinsic value of a stock option is the amount by which the market value of the underlying stock at the end of the related period exceeds the exercise price of the option.