Compensation Plans (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
RSUs, PSUs, and Director's Shares [Abstract]
Stock-based compensation expense	$ 6,344,000	$ 8,113,000
Cash Bonus Plan [Member]
Compensation plans
Accrued Cash Bonus Plan Expense	6,600,000	5,600,000
Restricted Stock Units (RSUs) [Member]
RSUs, PSUs, and Director's Shares [Abstract]
Number of Common Shares to be Received Upon Settlement	1
Stock-based compensation expense	2,800,000	3,000,000
Unrecognized stock based compensation expense	15,900,000
Performance Shares [Member]
RSUs, PSUs, and Director's Shares [Abstract]
Stock-based compensation expense	3,200,000	4,700,000
Unrecognized stock based compensation expense	14,900,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Low End of Range	0
Common stock awards vesting multiplier, high end of range	2
Share-based Compensation, Awards Other Than Options, Performance Measurement Period	3
Employee Stock Option [Member]
Stock option activity
Stock options outstanding at the end of the period (in shares)	39,088
Weighted-Average Exercise Price
Stock options outstanding at the end of the period (in dollars per share)	$ 20.87
Aggregate Intrinsic Value
Vested at the end of the period	$ 1,971,000