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Recent Accounting Pronouncements (Narrative) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Accounting Policies [Abstract]
Estimated reclassification of cumulative effect accumulated other comprehensive income to retained earnings for equity investments.	$ 2.0
Estimated reclassification of cumulative effect retained earnings to accumulated other comprehensive income for financial liabilities	$ 162.0

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- Definition

Cumulative equity adjustment for the adoption of ASU 2016-01.

+ References

No definition available.

+ Details

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X

- Definition

Cumulative equity adjustment for the adoption of ASU 2016-01.

+ References

No definition available.

+ Details

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X

- References

No definition available.

+ Details

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