Summary of Significant Accounting Policies Schedule of Revisions and Reclassifications - Statement of Operations (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Provision for income taxes	$ 90,982		$ 74,934		$ 37,357		$ 22,707		$ 17,729	[1]	$ 18,407	[1]	$ 21,598	[1]	$ 35,290	[1]	$ (225,980)	$ (93,024)		$ (90,111)
Net income	87,949		17,685		31,781		41,391		32,037		27,394		34,435		58,722		178,806	152,588		155,434
Net income attributable to common stockholders	87,794		17,651		25,922		41,102		29,318	[1]	26,779	[1]	33,615	[1]	57,620	[1]	172,469	147,332		153,845
Net income attributable to common stockholders, basic	$ 0.42	[2]	$ 0.08	[2]	$ 0.12	[2]	$ 0.19	[2]	$ 0.14	[2]	$ 0.13	[2]	$ 0.16	[2]	$ 0.27	[2]	$ 0.82			$ 0.71
Earnings per share, diluted	$ 0.42	[2]	$ 0.08	[2]	$ 0.12	[2]	$ 0.19	[2]	$ 0.14	[2]	$ 0.12	[2]	$ 0.16	[2]	$ 0.27	[2]	$ 0.81			$ 0.70
Financials as previously reported [Member]
Provision for income taxes																		(96,615)		(91,548)
Net income																		149,104	[3]	154,135	[3]
Net income attributable to common stockholders																		143,848		152,546
Net income attributable to common stockholders, basic																		$ 0.68		$ 0.71
Earnings per share, diluted																		$ 0.67		$ 0.70
Restatement Adjustment [Member]
Provision for income taxes																		3,484		1,299
Net income																		3,484	[3]	1,299	[3]
Net income attributable to common stockholders																		3,484		1,299
Net income attributable to common stockholders, basic																		$ 0.02		$ 0.00
Earnings per share, diluted																		$ 0.01		$ 0.00
Reclassifications for purchase price adjustments and discontinued operations [Member]
Provision for income taxes																		107		138
Net income																		0	[3]	0	[3]
Net income attributable to common stockholders																		0		0
Net income attributable to common stockholders, basic																		$ 0.00		$ 0.00
Earnings per share, diluted																		$ 0.00		$ 0.00
Financials as adjusted [Domain]
Provision for income taxes																		(93,024)		(90,111)
Net income																		152,588	[3]	155,434	[3]
Net income attributable to common stockholders																		$ 147,332		$ 153,845
Net income attributable to common stockholders, basic																		$ 0.70		$ 0.71
Earnings per share, diluted																		$ 0.68		$ 0.70

[1] See Note 2 for details related to the revision which was recorded for the quarter ended December 31, 2013. The revision reduced the provision for income taxes and increased net income attributable to common stockholders by $3.5 million and increased basic and diluted EPS by $0.02.

[2] Net income per share is computed independently for each of the quarters presented. Therefore, the sum of the quarters’ net income per share may not equal the total computed for the year.

[3] These revisions had no net impact on Net cash provided by operating, investing, or financing activities.