Share-Based Compensation (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended				3 Months Ended		6 Months Ended			6 Months Ended		1 Months Ended	3 Months Ended	6 Months Ended		12 Months Ended			3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		1 Months Ended	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011 Cliff Vesting [Member] Restricted Stock Grants [Member]	Jun. 30, 2011 Stock Options [Member]	Jun. 30, 2011 Restricted Stock [Member]	Jun. 30, 2010 Restricted Stock [Member]	Jun. 30, 2011 Restricted Stock [Member]	Jun. 30, 2010 Restricted Stock [Member]	Dec. 31, 2010 Restricted Stock [Member]	Jun. 30, 2011 Restricted Stock Unit [Member]	Dec. 31, 2010 Restricted Stock Unit [Member]	Jan. 31, 2011 Restricted Stock Grants [Member]	Jun. 30, 2010 Restricted Stock Grants [Member]	Jun. 30, 2011 Restricted Stock Grants [Member]	Jun. 30, 2010 Restricted Stock Grants [Member]	Dec. 31, 2008 Restricted Stock Grants [Member]	Jan. 11, 2011 Restricted Stock Grants [Member]	Dec. 31, 2010 Restricted Stock Grants [Member]	Jun. 30, 2011 Cash-Settled Restricted Stock Units [Member]	Jun. 30, 2010 Cash-Settled Restricted Stock Units [Member]	Jun. 30, 2011 Cash-Settled Restricted Stock Units [Member]	Jun. 30, 2010 Cash-Settled Restricted Stock Units [Member]	Dec. 31, 2010 Cash-Settled Restricted Stock Units [Member]	Jun. 30, 2011 Employee Stock Purchase Program [Member]	Jun. 30, 2010 Employee Stock Purchase Program [Member]	Jun. 30, 2011 Employee Stock Purchase Program [Member]	Jun. 30, 2010 Employee Stock Purchase Program [Member]	Jan. 31, 2011 Chief Executive Officer Specific Share-based Compensation [Member]	Jun. 30, 2011 Chief Executive Officer Specific Share-based Compensation [Member]	Jun. 30, 2011 CAGR Of 4% [Member]	Jun. 30, 2011 CAGR Of 20% or More [Member]
Share-based compensation, vesting period			four years or sooner		three years							over four years
Maximum vesting period of stock option						ten years
Number of shares of common stock available for future grants						4,600,000						300,000
Dividends assumed to pay						$ 0
Compensation cost of non-vested stock granted to employees, not yet recognized						8,000,000						7,600,000									3,600,000		3,600,000
Recognition period of compensation cost of non-vested stock granted, years						2.0						2.4											3.2
Restricted stock grants, market vesting condition																The vesting of restricted stock grants issued to certain of our employees was contingent upon multiple market conditions that were factored into the fair value of the restricted stock at grant date with cliff vesting after three years if the market conditions had been met.
Common stock earned as of the vesting date																			454,000
Shares issued by operation of the provisions of employment contracts																		65,000
Common stock distributed														339,000
Shares settled with cash upon the discretion of the Compensation Committee of the Board of Directors														115,000
Pre-tax, cash settled upon the discretion of the Compensation Committee of the Board of Directors														4,100,000
Expected term, years		6.3	5.2	6.3												3
Risk-free interest rate		2.70%	2.20%	3.10%												2.60%
Expected Dividend		0.00%	0.00%	0.00%
Expected volatility		44.70%	44.60%	45.20%												40.00%
Grant date fair value per restricted share							$ 22.17		$ 22.17		$ 19.52	$ 36.10	$ 27.68							$ 24.78	$ 33.12		$ 33.12		$ 28.13
Fair market value discount on common stock to eligible employees																												5.00%
Shares reserved for sale to employees																										1,000,000		1,000,000
Shares purchased by employees																										3,000	3,000	6,000	6,000
Incentive compensation award term																															three-year
CAGR, lower range																																4.00%
CAGR, higher range																																	20.00%
Chief executive officer specific share-based compensation, incentive compensation award amount lower range																																2,000,000
Chief executive officer specific share-based compensation, incentive compensation award amount higher range																																	9,000,000
Chief executive officer specific share-based compensation, condition																															He will not be eligible to receive an incentive compensation award if the Company's three-year CAGR is below 4%, and no incentive compensation award will be payable if the employment agreement is terminated prior to its expiration unless a change of control (as defined in the agreement) has occurred.
CAGR, during period																															below 4%
Total grant date economic value of restricted stock granted to Chief Executive Officer																														1,850,000
Share based compensation expense recognized	$ 1,011,000	$ 1,938,000	$ 2,503,000	$ 3,322,000			$ 1,405,000	$ 2,106,000	$ 3,080,000	$ 3,831,000					$ 425,000		$ 934,000				$ 285,000	$ 109,000	$ 1,038,000	$ 210,000							$ 268,000