Investments (Tables)

6 Months Ended

Jun. 30, 2014

Investments, Debt and Equity Securities [Abstract]

Schedule of Investments

At June 30, 2014 investments classified as available-for-sale securities were as follows:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Debt securities:
U.S. Treasury securities	$	524,663	$	151	$	—	$	524,814
Corporate debt securities	102,182		—		1,941		100,241
Preferred stock	3,270		217		—		3,487
	$	630,115	$	368	$	1,941	$	628,542

At December 31, 2013 investments classified as available-for-sale securities were as follows:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Debt securities:
U.S. Treasury securities	$	124,861	$	88	$	—	$	124,949
Corporate debt securities	24,236		—		2,213		22,023
	$	149,097	$	88	$	2,213	$	146,972

Contractual Maturities of Investments

The net carrying value and estimated fair value of investments classified as available-for-sale at June 30, 2014, by contractual maturity are shown in the following table. Actual maturities may differ from contractual maturities because certain borrowers have the right to call or prepay obligations.

	Amortized Cost		Fair Value
Due in one year or less	$	524,663	$	524,814
Due after one year through five years	102,182		100,241
	626,845		625,055
Preferred stock	3,270		3,487
	$	630,115	$	628,542