Commitments and Contingencies - Summary of Company's Outstanding Unfunded Investment Commitments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]
Commitments	$ 311,000	$ 291,000
Commitments, Funded	179,050	176,760
Commitments, Unfunded	$ 131,950	$ 114,240