Investments - Amortized Cost and Fair Value of Securities Available for Sale (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 155,136	$ 106,977
Estimated Fair Value	153,893	102,105
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	155,136	106,977
Gross Unrealized Gains	1,332	706
Gross Unrealized Losses	(2,575)	(5,578)
Estimated Fair Value	$ 153,893	$ 102,105