Accounting Changes (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
New Accounting Pronouncement, Early Adoption [Line Items]
Recognition of excess tax benefits	$ 0	$ 0
Increase in net cash provided by operating activities	51,836	30,529
Increase to net cash provided by financing activities	(20,100)	(24,251)
Accounting Standards Update 2016-09 [Member] \| New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Increase in net cash provided by operating activities		$ 413
Increase to net cash provided by financing activities	$ 413

Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount

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- Definition

Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

+ References

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- Definition

Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3521-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3536-108585

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