Share-Based Compensation (Narrative) (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended								1 Months Ended	12 Months Ended					1 Months Ended	12 Months Ended					12 Months Ended				1 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended			12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2011 Stock Options [Member]	Dec. 31, 2010 Stock Options [Member]	Dec. 31, 2009 Stock Options [Member]	Dec. 31, 2011 Restricted Stock And Restricted Stock Unit Grants [Member]	Jan. 31, 2012 Performance Shares [Member]	Dec. 31, 2011 Restricted Stock [Member]	Dec. 31, 2010 Restricted Stock [Member]	Dec. 31, 2009 Restricted Stock [Member]	Dec. 31, 2011 Restricted Stock Unit [Member]	Dec. 31, 2010 Restricted Stock Unit [Member]	Jan. 31, 2011 Restricted Stock Grants [Member]	Dec. 31, 2011 Restricted Stock Grants [Member]	Dec. 31, 2010 Restricted Stock Grants [Member]	Dec. 31, 2009 Restricted Stock Grants [Member]	Dec. 31, 2008 Restricted Stock Grants [Member]	Jan. 11, 2011 Restricted Stock Grants [Member]	Dec. 31, 2011 Cash-Settled Restricted Stock Units [Member]	Dec. 31, 2010 Cash-Settled Restricted Stock Units [Member]	Dec. 31, 2009 Cash-Settled Restricted Stock Units [Member]	Dec. 31, 2011 Employee Stock Purchase Program [Member]	Jan. 31, 2011 Chief Executive Officer Specific Share-Based Compensation [Member]	Dec. 31, 2011 Chief Executive Officer Specific Share-Based Compensation [Member]	Dec. 31, 2011 CAGR Of 4% [Member]	Dec. 31, 2011 CAGR Of 20% Or More [Member]	Dec. 31, 2011 Cliff Vesting [Member] Restricted Stock Grants [Member]	Jan. 31, 2012 Maximum [Member]	Dec. 31, 2011 Maximum [Member] Stock Options [Member]	Jan. 31, 2012 Minimum [Member]	Dec. 31, 2010 Chief Financial Officer [Member]	Dec. 31, 2010 Chief Financial Officer [Member] Stock Options [Member]	Dec. 31, 2010 Chief Financial Officer [Member] Restricted Stock [Member]	Dec. 31, 2010 Board Member [Member]	Dec. 31, 2010 Board Member [Member] Restricted Stock Unit [Member]	Dec. 31, 2010 Board Member [Member] Cash-Settled Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, vesting period in years					four								four								four								three		ten
Share-based compensation, shares vested	2,264																																	86
Share-based compensation, shares non-vested										281	496		69	23			242				149	72													19
Share-based compensation, vesting of restricted stock units										255			29			339					18																4	23
Compensation expense																																	$ 800,000			$ 300,000
Number of shares of common stock available for future grants					4,800			500																700
Compensation cost of non-vested stock granted to employees, not yet recognized					6,100,000								5,400,000								3,500,000
Recognition period of compensation cost of non-vested stock granted, years					2.3								2.3								2.8
Number of companies in peer group for Total Stockholder Return program				12
Minimum Percentile of peer group outcome				75
Common stock earned as of the vesting date																				454
Shares issued by operation of the provisions of employment contracts																			65
Performance shares awards in a range																														20.00%		0.00%
Common stock distributed									25						339
Shares settled with cash upon the discretion of the Compensation Committee of the Board of Directors									5						115
Pre-tax, cash settled upon the discretion of the Compensation Committee of the Board of Directors									1,700,000						4,100,000
Expected term, years	5.2	6.3	6.3													3
Risk-free interest rate	2.20%	3.00%	1.90%													2.60%
Expected dividend	0.00%	0.00%	0.00%		0.00%
Expected volatility	44.60%	45.10%	43.90%													40.00%
Grant date fair value per restricted share										$ 24.28	$ 19.52		$ 36.47	$ 27.68		$ 24.78	$ 24.78				$ 32.97	$ 28.13
Fair market value discount on common stock to eligible employees																								5.00%
Shares reserved for sale to employees	4,708																							1,000
Number of distinct population of optionees	3
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
Total grant date economic value of restricted stock granted to Chief Executive Officer																									1,850,000
Share-based compensation expense recognized					4,321,000	5,845,000	4,820,000			5,509,000	7,360,000	6,954,000					1,740,000	1,962,000			1,320,000	492,000				362,000
Total grant-date fair value of awards granted																						4,000,000
Aggregate intrinsic value of the outstanding awards	$ 18,095,000																				$ 4,900,000