Stock-Based Compensation Expense (Narrative) (Details) (USD $)	0 Months Ended	12 Months Ended
	Apr. 20, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based awards, minimum vesting period, years		one
Share-based awards, maximum vesting period, years		five
Intrinsic value of stock options exercised		$ 7,900,000	$ 15,100,000	$ 5,800,000
Recognized tax benefits related to stock-based compensation		10,000,000	5,800,000	100,000
Stock options granted during the period		401,500
Stock-based compensation		27,069,000	15,694,000	307,000
Increase in number of shares available for issuance under incentive plan	4,470,000
Common stock, shares authorized		150,000,000	150,000,000
Stock-based compensation accruals reduction amount				7,800,000
Proceeds from exercise of stock options		2,230,000	7,135,000	4,153,000
Fair market value of share	100,000
Reduced Incentive Plan awards number of shares	1.6
Common stock shares authorized for issuance to directors		200,000
Restricted Stock [Member]
Share-based awards, minimum vesting period, years		one
Share-based awards, maximum vesting period, years		five
Compensation cost not yet recognized for nonvested shares		4,300,000
Remaining weighted-average period for recognition of compensation cost, years		2.2
Incentive Plans [Member]
Stock-based compensation		27,100,000	15,700,000	300,000
Shares available for grant		4,723,670
Non Employee Directors Plan [Member]
Common stock, shares authorized	100,000
Shares available for grant		49,875
Performance Unit Awards [Member]
Compensation cost not yet recognized for nonvested shares		11,800,000
Remaining weighted-average period for recognition of compensation cost, years		1.0
Number of common stock shares		1
Stock Option [Member]
Share-based awards, minimum vesting period, years		three
Share-based compensation, term of awards, years		10
Compensation cost not yet recognized for nonvested shares		6,200,000
Stock options granted during the period		401,500	389,000	1,255,500
Remaining weighted-average period for recognition of compensation cost, years		1.3
Proceeds from exercise of stock options		2,200,000
Tax benefit from stock options exercised		$ 2,900,000
Maximum [Member]
Increase in number of shares available for issuance under incentive plan	7,470,000
Maximum [Member] | Performance Unit Awards [Member]
Percentage of earnings		200.00%
Specific performance criteria period, years		2
Minimum [Member] | Performance Unit Awards [Member]
Percentage of earnings		0.00%
Specific performance criteria period, years		1
Two-Year Measurement Period [Member]
Percentage of earnings distributed		50.00%
One-Year Vesting Period Thereafter [Member]
Percentage of earnings distributed		50.00%
Director [Member]
Allocation of shares				700
All Directors [Member]
Allocation of shares				5,600