Summary of Significant Accounting Policies (Narrative) (Details) $ / shares in Units, $ in Thousands	1 Months Ended							3 Months Ended
	May. 31, 2016 $ / shares	Mar. 31, 2016 $ / shares	Nov. 30, 2015 $ / shares	Aug. 31, 2015 $ / shares	May. 31, 2015 $ / shares	Mar. 31, 2015	Feb. 28, 2015 $ / shares	Apr. 30, 2016 USD ($) $ / shares	May. 02, 2015 USD ($) $ / shares	Jan. 30, 2016 USD ($)
Summary of Significant Accounting Policies [Line Items]
Stock split, conversion ratio						2
Cash dividends declared per share (in dollars per share) | $ / shares		$ 0.1350	$ 0.1175	$ 0.1175	$ 0.1175		$ 0.1175	$ 0.1350	$ 0.1175
Reclassification into long-term deferred tax liabilities								$ 140,801	$ 72,786	$ 130,088
Property, Plant and Equipment [Member]
Summary of Significant Accounting Policies [Line Items]
Property and equipment purchased but not yet paid								$ 5,600	18,000
Subsequent Event [Member]
Summary of Significant Accounting Policies [Line Items]
Cash dividends declared per share (in dollars per share) | $ / shares	$ 0.1350
Accounting Standards Update 2015-17 [Member]
Summary of Significant Accounting Policies [Line Items]
Reclassification out of current deferred tax assets									12,600
Reclassification into long-term deferred tax liabilities									$ 12,600