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Stockholders' Equity Dividends Declared (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Dividends Declared [Line Items]
Dividends declared per Class A common share (in dollars per share)	$ 0.55	$ 0.60	$ 2.14	$ 1.99
Quarterly
Dividends Declared [Line Items]
Dividends declared per Class A common share (in dollars per share)	0.55	0.60	1.11	1.20
Special Annual
Dividends Declared [Line Items]
Dividends declared per Class A common share (in dollars per share)	$ 0	$ 0	$ 1.03	$ 0.79

X

- Definition

Aggregate dividends paid during the period for each share of common stock outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

+ Details

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X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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