Capital Transactions (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2014
$8 to $16
Stock options, exercise price
Exercise price range, low end of range (in dollars per share)	$ 8
Exercise price range, high end of range (in dollars per share)	$ 16
Options Outstanding
Number of options outstanding (in shares)	1,482,592
Options outstanding, Weighted Average Remaining Contractual Life	3 years 2 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 14.09
Options Exercisable
Number of options Exercisable (in shares)	918,584
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 14.98
$17 to $22
Stock options, exercise price
Exercise price range, low end of range (in dollars per share)	$ 17
Exercise price range, high end of range (in dollars per share)	$ 22
Options Outstanding
Number of options outstanding (in shares)	1,108,895
Options outstanding, Weighted Average Remaining Contractual Life	1 month 6 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 17.13
Options Exercisable
Number of options Exercisable (in shares)	1,108,895
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 17.13
$23 to $28
Stock options, exercise price
Exercise price range, low end of range (in dollars per share)	$ 23
Exercise price range, high end of range (in dollars per share)	$ 28
Options Outstanding
Number of options outstanding (in shares)	296,587
Options outstanding, Weighted Average Remaining Contractual Life	1 month 6 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 25.80
Options Exercisable
Number of options Exercisable (in shares)	296,587
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 25.80
$8 to $28
Stock options, exercise price
Exercise price range, low end of range (in dollars per share)	$ 8
Exercise price range, high end of range (in dollars per share)	$ 28
Options Outstanding
Number of options outstanding (in shares)	2,888,074
Options outstanding, Weighted Average Remaining Contractual Life	1 year 8 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 16.46
Options Exercisable
Number of options Exercisable (in shares)	2,324,336
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 17.39