Noncontrolling Interests (Preferred Stockholders' Equity in Subsidiaries) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Noncontrolling Interest [Line Items]
Combined voting power of all classes of capital stock of PBIH	25.00%
Combined voting power of all classes of capital stock remaining	75.00%
Preferred stock dividend rate	4.00%	4.00%
Preferred stock, cumulative dividend increase interval if outstanding once callable	6 months
Dividends in arrears	$ 0		$ 0
Redeemable Preferred Stock Member
Noncontrolling Interest [Line Items]
Shares of outstanding perpetual voting preferred stock (in shares)	300,000
Shares of outstanding perpetual voting preferred stock	$ 300,000,000
Preferred stock dividend rate	6.125%
Preferred dividend rate if stock is not redeemed	50.00%
Preferred stock, perpetual voting, dividend increase percentage each interval once shares become callable	50.00%