Stockholders' Equity - Additional Information (Detail) (USD $)
In Millions, except Per Share data, unless otherwise specified |
12 Months Ended | |
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Dec. 31, 2013
Vote
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Dec. 31, 2012
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Class A common stock [Member]
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Schedule of Capitalization, Equity [Line Items] | ||
Common stock, voting rights per share | 1 | |
Cash dividend paid per share | $ 0.125 | $ 0.120 |
Cash dividend paid per share amount | $ 11.0 | $ 10.3 |
Class B common stock [Member]
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Schedule of Capitalization, Equity [Line Items] | ||
Common stock, voting rights per share | 10 | |
Cash dividend paid per share | $ 0.125 | $ 0.120 |
Cash dividend paid per share amount | 11.0 | 10.3 |
Class U common stock [Member]
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Schedule of Capitalization, Equity [Line Items] | ||
Cash dividend paid per share | $ 0.125 | $ 0.120 |
Cash dividend paid per share amount | $ 11.0 | $ 10.3 |