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Capital Stock - Additional Information (Detail) - USD ($) | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2016 | Mar. 31, 2015 | Feb. 04, 2016 | Feb. 28, 2015
Class of Stock [Line Items] |  |  |  |
Stock repurchase authorized amount |  |  | $ 250,000,000 |
Shares repurchased and retired (in shares) | 1,356,199 | 590,713 |  |
Common stock shares repurchased price per share | $ 24.35 | $ 22.51 |  |
Aggregate amount of common stock shares repurchased | $ 33,017,000 | $ 13,298,000 |  |
Expenses related to stock purchases | $ 27,000 | $ 12,000 |  |
February 2015 Stock Repurchase Program |  |  |  |
Class of Stock [Line Items] |  |  |  |
Stock repurchase authorized amount |  |  | $ 500,000,000 |
Maximum |  |  |  |
Class of Stock [Line Items] |  |  |  |
Stock repurchase authorized amount |  |  |  | $ 250,000,000

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- Definition The cash outflow to reacquire common stock during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 + Details
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- Definition Number of shares that have been repurchased and retired during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 + Details
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