Stock-Based Compensation and Equity (Narratives) (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation expenses	$ 7,045,000	$ 9,149,000
Tax benefit from stock based compensation expense	17,300,000	16,000,000
Risk free interest rate	0.65%
Fair value assumptions expected volatility rate	25.89%
Fair value assumptions expected volatility rate peer index	21.77%
Fair value assumptions expected dividend rate	0.00%
Fair value of vested stock	23,900,000
Deferred compensation, shares	889,863
Deferred compensation obligation	29,342,000		11,354,000
Unrecognized stock based compensation expense	41,200,000
Weighted-average remaining term	1 year 10 months 10 days
Options exercised in period	18,286
Options exercised during the period, aggregate intrinsic value	$ 600,000
Stock options exercisable	493,734
Officers | WPCI
Redeemable Noncontrolling Interest
Minority interest ownership interest	7.70%