Fair Value Measurements, Call Option FV Assumption Table (Details) (USD $) | Sep. 30, 2011
basispoints
years | |||||||||||
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| Fair Value Disclosures [Abstract] | ||||||||||||
| Stock price at September 30, 2011 | $ 44.28 | [1] | ||||||||||
| Quarterly dividend yield (per share) | $ 0.24 | [2] | ||||||||||
| Risk-free interest rate | 0.56% | [3] | ||||||||||
| Credit spread (basis points) | 700 | [4] | ||||||||||
| Expected volatility rate | 36.00% | [5] | ||||||||||
| Constant Maturity Treasury Rate Specified Year One | 5 | |||||||||||
| Constant Maturity Treasury Rate Specified Year Two | 3 | |||||||||||
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