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Total cost of shares repurchased divided by the total number of shares repurchased.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

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Number of shares that have been repurchased during the period and are being held in treasury.

+ References

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the par value method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

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-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

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-Subparagraph (SX 210.3-04)

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-Section 45

-Paragraph 1

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Stock Repurchase Program (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended					51 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares repurchased as part of stock repurchase programs		4,994,578us-gaap_TreasuryStockSharesAcquired	15,812,566us-gaap_TreasuryStockSharesAcquired	7,185,257us-gaap_TreasuryStockSharesAcquired	1,150,000us-gaap_TreasuryStockSharesAcquired	29,342,401us-gaap_TreasuryStockSharesAcquired
Cost of shares repurchased	$ 6,980	$ 193,434	$ 436,419	$ 125,341	$ 19,138	$ 781,312
Weighted Average Price		$ 38.73	$ 27.60	$ 17.44	$ 16.64	$ 26.63
Repurchase Of Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares repurchased as part of stock repurchase programs	200,000
Cost of shares repurchased	$ 6,980
Weighted Average Price	$ 34.90