Stockholders' Equity (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Class of Stock [Line Items]
Maximum dividend payment which may be paid without prior approval from Colorado Division of Insurance	$ 100.5
Common Class A [Member]
Class of Stock [Line Items]
Dividend declared	$ 0.36	$ 0.36
Common Class B [Member]
Class of Stock [Line Items]
Dividend declared	$ 0.18	$ 0.18