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Adoption of New Accounting Standards (Details) - USD ($) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2017 | Mar. 31, 2017 | Jun. 30, 2016 | Jun. 30, 2017 | Jun. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |
Recognized a discrete tax benefit | $ 200,000 | $ 1,800,000 |  | $ 2,000,000 |
Tax benefit (expense) recognized as additional paid-in capital |  |  | $ 300,000 |  | $ (100,000)
Reclassified tax benefits to operating activities |  |  |  | 172,173,180 | 131,076,603
Cash flows from operating activities |  |  |  | $ 263,557,719 | 255,129,954
Additional Paid-in Capital [Member] |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |
Tax benefit (expense) recognized as additional paid-in capital |  |  | 300,000 |  | (100,000)
Tax benefit recognized as additional paid-in capital |  |  | 800,000 |  | 1,000,000
Tax expense recognized as additional paid-in capital |  |  | $ 500,000 |  | 1,100,000
Accounting Standards Update 2016-09 [Member] |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |
Reclassified tax benefits to operating activities |  |  |  |  | 1,700,000
Cash flows from operating activities |  |  |  |  | $ 1,700,000
Effect on earnings per share (in dollars per share) | $ 0.01 |  |  | $ 0.01 |

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- Definition Amount of increase in additional paid in capital (APIC) resulting from a tax benefit associated with share-based compensation plan other than an employee stock ownership plan (ESOP). Includes, but is not limited to, excess tax benefit. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 740 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=79981250&loc=d3e23524-113945 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644 + Details
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